Non-personal basic service point / access point (pcp/ap) communication device, non-pcp/ap communication method, pcp/ap communication device and pcp/ap communication method

ABSTRACT

A non-personal basic service set control point/access point (non-PCP/AP) communication apparatus includes a reception circuit, an estimation circuit, and a transmission circuit. The reception circuit receives a Directional Multi-Gigabit (DMG) Beacon frame including a sector sweep (SSW) field, the SSW field including a Parameter subfield indicating a value obtained by using a transmission Equivalent Isotropic Radiated Power (EIRP) of a PCP/AP communication partner apparatus and a reception antenna gain of the PCP/AP communication partner apparatus. The estimation circuit estimates an expected reception power at the PCP/AP communication partner apparatus by using the value of the Parameter subfield, and checks inequality between the estimated expected reception power and a receiver sensitivity value. The transmission circuit transmits a frame for Association Beamforming Training (A-BFT) if the estimated expected reception power is larger than the receive sensitivity value.

BACKGROUND 1. Technical Field

The present disclosure relates to a non-personal basic servicepoint/access point (PCP/AP) communication device, a non-PCP/APcommunication method, a PCP/AP communication device and a PCP/APcommunication method.

2. Description of the Related Art

IEEE 802.11 is one of wireless LAN related standards, one of which is,for example, the IEEE 802.11ad (hereinafter referred to as “11adstandard”) (e.g., see IEEE 802.11adTM-2012 pp 278-314). Beamforming (BF)technology is used in the 11ad standard. Beamforming is a method wherecommunication is performed by changing the directionality of one or moreantennas of a transmission unit and reception unit included in awireless terminal, to set antenna directionality so that communicationquality, such as reception strength for example, is optimal.

SUMMARY

However, communication areas of wireless terminals are not taken intoconsideration, there are cases where, even if a first wireless terminalcan receive a frame used for training for beamforming from a secondwireless terminal, it is difficult for the second wireless terminalreceive a frame used for training for beamforming from the firstwireless terminal, and it is difficult for the wireless terminals toestablish a wireless link.

In communication device according to an aspect of the presentdisclosure, a wireless device (STA) can determine whether or not an SSWframe in A-BFT will reach a communication device (AP) or not, therebycontributing to providing of a communication device and communicationmethod where unnecessary transmission of SSW frames can be avoided, soelectric power consumption of the communication device (STA) can bereduced, and occurrence of unnecessary interference waves as to otherSTAs can be reduced.

In one general aspect, the techniques disclosed here feature Anon-personal basic service point/access point (PCP/AP) communicationdevice, that includes a reception circuit that receives a DMG Beaconframe, a judging circuit that judges whether or not to transmit a frameused for beamforming training (BFT), using information relating toreception antenna gain of a PCP/AP communication device included in aDMG Beacon frame and information relating to reception power of a DMGBeacon frame, and a transmission circuit that transmits the frame usedfor BFT in a case of the judging circuit having judged to transmit theframe used for BFT.

According to a communication device and communication method of anaspect of the present disclosure, a wireless device (STA) can determinewhether or not an SSW frame in A-BFT will reach a communication device(AP) or not, and unnecessary transmission of SSW frames can be avoided,so electric power consumption of the communication device (STA) can bereduced, and occurrence of unnecessary interference waves as to otherSTAs can be reduced.

It should be noted that general or specific embodiments may beimplemented as a system, a device, a method, an integrated circuit, acomputer program, a storage medium, or any selective combination ofsystem, device, method, integrated circuit, computer program, andstorage medium.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of SLS procedures accordingto the present disclosure;

FIG. 2 is a diagram illustrating an example of a method of a PCP/AP andnon-AP STA establishing a wireless link according to the presentdisclosure;

FIG. 3A is a diagram illustrating an example of PCP/AP operations in adownlink sector sweep regarding a non-PCP/AP STA according to thepresent disclosure;

FIG. 3B is a diagram illustrating an example of non-PCP/AP STAoperations in an uplink sector sweep regarding a PCP/AP according to thepresent disclosure;

FIG. 3C is a diagram illustrating an example of PCP/AP operations indownlink data transmission as to a non-PCP/AP STA according to thepresent disclosure;

FIG. 3D is a diagram illustrating an example of non-PCP/AP STAoperations in uplink data transmission as to a PCP/AP according to thepresent disclosure;

FIG. 4 is a diagram illustrating an example of the configuration of acommunication device according to a first embodiment of the presentinvention;

FIG. 5 is a diagram illustrating an example of a DMB Beacon frame that acommunication device (AP) according to the first embodiment of thepresent disclosure transmits;

FIG. 6 is a diagram illustrating an example of correlation between avalue of a TX EIRP field and an EIRP value, according to the firstembodiment of the present disclosure;

FIG. 7 is a diagram illustrating another example of correlation betweena value of a TX EIRP field and an EIRP value, according to the firstembodiment of the present disclosure;

FIG. 8 is a diagram illustrating an example of correlation between avalue of an A-BFT RX Antenna Gain field and a value of reception antennagain of the communication device (AP) in A-BFT, according to the firstembodiment of the present disclosure;

FIG. 9 is a diagram illustrating another example illustratingcorrelation between a value of an A-BFT RX Antenna Gain field and avalue of reception antenna gain, according to the first embodiment ofthe present disclosure;

FIG. 10 is a flowchart illustrating an example of reception processingof the DMG Beacon frame in FIG. 5 by a communication device (STA)according to the first embodiment of the present disclosure;

FIG. 11 is a flowchart illustrating another example of receptionprocessing of the DMG Beacon frame in FIG. 5 by a communication device(STA) according to the first embodiment of the present disclosure;

FIG. 12A is a diagram illustrating an example of values of receptionsensitivity levels as to MCS in the 11ad standard, according to thefirst embodiment of the present disclosure;

FIG. 12B is a diagram illustrating an example of values of maximumthroughput as to MCS in the 11ad standard, according to the firstembodiment of the present disclosure;

FIG. 13 is a diagram illustrating an example of procedures for acommunication device (AP) and communication device (STA) to performcommunication, according to a second embodiment of the presentdisclosure;

FIG. 14 is a diagram illustrating an example of a format of a DMG Beaconframe according to the second embodiment of the present disclosure;

FIG. 15 is a diagram illustrating an example of a value of a TX EIRPfield according to the second embodiment of the present disclosure;

FIG. 16 is a diagram illustrating an example of a value of an A-BFT RXAntenna Gain field according to the second embodiment of the presentdisclosure;

FIG. 17 is a diagram illustrating an example of a Probe Request frameaccording to the second embodiment of the present disclosure;

FIG. 18 is a diagram illustrating another example of a format of a DMGBeacon frame according to the second embodiment of the presentdisclosure;

FIG. 19 is a diagram illustrating an example of values of a DifferentialGain field according to the second embodiment of the present disclosure;

FIG. 20 is a diagram illustrating another example of a format of a ProbeResponse frame according to the second embodiment of the presentdisclosure;

FIG. 21 is a diagram illustrating an example of values of a RelativeBeamed TX EIRP field according to the second embodiment of the presentdisclosure;

FIG. 22 is a diagram illustrating an example of procedures for acommunication device (AP) and communication device (STA) to performcommunication, according to a third embodiment of the presentdisclosure;

FIG. 23 is a diagram illustrating an example of a format of a DMG Beaconframe according to the third embodiment of the present disclosure;

FIG. 24 is a diagram illustrating another example of a DMG Beacon frameaccording to the third embodiment of the present disclosure;

FIG. 25 is a diagram illustrating an example of procedures of an AP1according to the third embodiment of the present disclosure including anEDMG TX RX Info field relating an AP2 in a Neighbor Report Responseframe and transmitting;

FIG. 26 is a diagram illustrating an example of a Neighbor ReportResponse frame according to the third embodiment of the presentdisclosure;

FIG. 27 is a diagram illustrating an example of procedures for acommunication device (AP) and communication device (STA) to performcommunication, according to a fourth embodiment of the presentdisclosure;

FIG. 28 is a diagram illustrating an example of a Feedback frameaccording to the fourth embodiment of the present disclosure;

FIG. 29 is a diagram illustrating a format of an RTS frame in the 11adstandard according to the fourth embodiment of the present disclosure;

FIG. 30 is a diagram illustrating a format of ESE in the 11ad standardaccording to the fourth embodiment of the present disclosure;

FIG. 31 is a diagram illustrating another example of a format of a DMGBeacon frame according to a modification of the first and secondembodiments of the present disclosure;

FIG. 32 is a diagram illustrating an example of a relation between avalue of the Differential Gain field and a value of(EIRP_Beacon-RxGain_ABFT-ADD_GAIN_AP), according to a modification ofthe first and second embodiments of the present disclosure;

FIG. 33 is a diagram illustrating an example of a DMG Beacon frameaccording to a fifth embodiment of the present disclosure;

FIG. 34 is a diagram illustrating an example of a value of an APSelection Parameter field according to the fifth embodiment of thepresent disclosure;

FIG. 35 is a flowchart illustrating reception processing of the DMGBeacon frame in FIG. 33 by a communication device (STA) 100 b accordingto the fifth embodiment of the present disclosure;

FIG. 36 is a diagram illustrating an example of processing proceduresfor Asymmetric Beamforming Training according to the fifth embodiment ofthe present disclosure;

FIG. 37 is a diagram illustrating an example of a format of a DMB Beaconpacket according to the fifth embodiment of the present disclosure;

FIG. 38 is a diagram illustrating an example of a format of an SSW fieldaccording to the fifth embodiment of the present disclosure;

FIG. 39 is a diagram illustrating an example of a format of an EDMG ESEaccording to the fifth embodiment of the present disclosure;

FIG. 40 is a diagram illustrating an example of a DMG Beacon frametransmitted by a communication device (AP) 100 a according to a sixthembodiment of the present disclosure; and

FIG. 41 is a flowchart illustrating reception processing of the DMGBeacon frame in FIG. 40 by a communication device (AP) 100 b accordingto the sixth embodiment of the present disclosure.

DETAILED DESCRIPTION

In the 11ad standard, procedures called Sector Level Sweep (SLS) arestipulated, to select, from multiple antenna directionality settings(hereinafter referred to as “sector”), an optimal sector. FIG. 1 is adiagram illustrating an example of SLS procedures. SLS is performedbetween two terminals (hereinafter referred to as “STA”, meaningStation). Note that hereinafter, one STA will be referred to asInitiator, and the other as Responder.

First, the Initiator transmits multiple Sector Sweep (SSW) includingsector Nos. in the SSW frame while changing sectors. This transmissionprocessing is called Initiator Sector Sweep (ISS). In ISS, the Responsemeasures the reception quality of each SSW frame, and identifies thesector No. of the SSW frame of which the reception quality was the best.This sector at the Initiator corresponding to the sector No. is referredto as the best sector of the Initiator.

Next, the Responder transmits multiple SSW frames while changingsectors. This transmission processing is called Responder Sector Sweep(RSS). In a RSS, the Responder includes a No. of a best sector of theInitiator identified in ISS in the SSW frames and transmits. In RSS, theInitiator measures the reception quality of each SSW frame, andidentifies the sector No. included in the SSW frames of which receptionquality was the best. The sector at the Responder corresponding to thissector No. is referred to as best sector of the Responder.

Finally, the Initiator includes the No. of the best sector of theResponder identified in RSS in an SSW Feedback (SSW-FB) frame, andtransmits. The Responder may, upon receiving the SSW-FB, transmit anSSW-ACK (SSW Acknowledgement) indicating that the SSW-FB has beenreceived.

Although SLS has been described for performing beam forming training fortransmission Transmitter Sector Sweep (TXSS), SLS may be used for beamforming training for reception Receiver Sector Sweep (RXSS). A STA thattransmits SSW frames sequentially transmits multiple SSW frames insingle sectors, and a STA that receives SSW frames switches the sectorsof the reception antennas for each SSW frame to receive.

In the 11ad standard, a part of STAs are STAs called Personal basicservice point (PCP) and Access point (AP) (hereinafter referred to asPCP/AP). STAs that are not a PCP/AP are referred to as non-PCP/AP STA.Upon starting communication, a non-PCP/AP STA first establishes awireless link with a PCP/AP.

FIG. 2 illustrates an example of a method for establishing a wirelesslink between a PCP/AP and a non-PCP/AP STA. The PCP/AP transmitsmultiple Directional Multi-Gigabit Beacon (DMG Beacon) frames whilechanging sectors.

In the 11ad standard, the duration of the PCP/AP transmitting a DMGBeacon is called a Beacon Transmission Interval (BTI). A period calledAssociation Beamforming Training (A-BFT) may be set following the BTI.

In the A-BFT, A STA1 (non-PCP/AP STA) transmits multiple SSW frameswhile changing sectors. In a case where SSW frames are received inA-BFT, the PCP/AP includes information identifying SSW frames of whichthe reception quality was good in a SSW-FB (SSW Feedback) frame, andtransmits to the STA1.

As described above, in a case of having received a DMG Beacon, anon-PCP/AP STA transmits SSW frames in the A-BFT, and establishes awireless link with the PCP/AP. However, the antennas of the PCP/AP andnon-PCP/AP STA do not take into consideration communication area of theantenna, so there are cases where it is difficult for the PCP/AP toreceive SSW frames in A-BFT even if the non-PCP/AP STA is capable ofreceiving DMG Beacon frames, and establishing of a wireless link betweenthe PCP/AP and non-AP STA is difficult. Also, the non-AP STA transmitsunnecessary SSW frames even though establishing of a wireless linkbetween the PCP/AP and non-AP STA is difficult, which increases electricpower consumption, and causes unnecessary interference for other STAs.

FIG. 3A illustrates an example of operations of a PCP/AP (hereinafter,communication device (AP) 100 a) in a downlink sector sweep as to anon-PCP/AP STA (hereinafter, communication device (STA) 100 b). Adownlink sector sweep is processing of the PCP/AP transmitting DMGBeacon frames in FIG. 2 , for example. A downlink sector sweep may alsobe the ISS in FIG. 1 .

The communication device (AP) 100 a uses a transmitting array antenna106 (see FIG. 4 ) to transmit DMG Beacon frames while changing sectors.The best sector is unknown, i.e., optimal settings of a receiving arrayantenna 116 (see FIG. 4 ) for communicating with the communicationdevice (AP) 100 a are unknown to the communication device (STA) 100 b,so the communication device (STA) 100 b performs DMG Beacon receptionusing a receiving quasi-omnidirectional (q-omni) antenna 115 (see FIG. 4).

FIG. 3B illustrates an example of operations of the non-PCP/AP STA(communication device (STA) 100 b) in an uplink sector sweep as to thePCP/AP (communication device (AP) 100 a). An uplink sector sweep isprocessing of the non-PCP/AP STA transmitting SSW frames in the A-BFT inFIG. 2 , for example. Note that FIG. 3B illustrates a state where thecommunication device (AP) 100 a does not receive SSW frames of thecommunication device (STA) 100 b.

The communication device (STA) 100 b transmits SSW frames while changingsectors, using the transmitting array antenna 106. The best sector isunknown, i.e., optimal settings of the receiving array antenna 116 forcommunicating with the communication device (STA) 100 b are unknown tothe communication device (AP) 100 a, so the communication device (AP)100 a performs SSW frame reception using the receiving q-omni antenna115.

The gain is different between the transmitting array antennas 106 (seeFIG. 4 ) and receiving q-omni antennas 115 of the communication device(AP) 100 a and communication device (STA) 100 b, so in FIG. 3A thecommunication device (STA) 100 b receives DMG Beacons, while in FIG. 3 bthe communication device (AP) 100 a does not receive SSW frames.

For example, the communication device (AP) 100 a has the transmittingarray antenna 106 that includes a great number of elements, and thetransmitting array antenna 106 of the communication device (STA) 100 bhas a smaller number of antenna elements as compared to thecommunication device (AP) 100 a. In this case, the transmitting antennagain of the communication device (AP) 100 a is great, and the inputpower to the transmitting array antenna is great. That is to say, thecommunication device (AP) 100 a has greater EIRP (Equivalent IsotropicRadiated Power) as compared to the communication device (STA) 100 b.

In a case where the communication device (STA) 100 b receives one ormore DMG Beacons or SSW frames in the downlink sector sweep in FIG. 3A,the communication device (AP) 100 a receives one or more SSW frames inan uplink sector sweep that is omitted from illustration, communicationbetween the communication device (AP) 100 a and communication device(STA) 100 b is established. At this time, the best sector is known tothe communication device (AP) 100 a and communication device (STA) 100b.

After the sector sweep, the communication device (AP) 100 a andcommunication device (STA) 100 b may carry out procedures for BeamRefinement Protocol (BRP) stipulated in the 11ad standard to performbeamforming training with even higher precision. BRP enables thecommunication device (AP) 100 a and communication device (STA) 100 b tostrengthen directionality of the best sector and increase gain.

However, it is difficult for the communication device (AP) 100 a todecide a best sector with increased gain by the downlink sector sweep inFIG. 3A. The reason is that a sector with increased gain has strongdirectionality and the beam width is small, so a great number of DMGBeacon and SSW frames need to be transmitted in the sector sweep for theDMG Beacon and sector frames to reach the communication device (STA) 100b, so the sector sweep takes a greater amount of time.

On the other hand, it is difficult for the communication device (AP) 100a to perform BRP before the sector sweep is completed. The reason isthat the best sector is unknown to the communication device (AP) 100 a,so it is difficult to get the communication device (STA) 100 b toreceive a BRP packet for performing BRP. That is to say, thecommunication device (AP) 100 a can reduce the time for the sector sweepby mid-level directionality illustrated in FIG. 3 , i.e., broadening thebeam width in FIG. 3C, and once the best sector has been decided, useBRP to decide the best sector with increased gain.

After having decided the best sector for the transmitting array antenna106 by the sector sweep, the communication device (AP) 100 a andcommunication device (STA) 100 b may carry out the BRP procedures andperform training for the receiving array antenna 116. Accordingly, thecommunication device (AP) 100 a and communication device (STA) 100 bdecide the best sector for the receiving array antenna 116.

Note that after having decided the best sector for the transmittingarray antenna 106, the communication device (AP) 100 a and communicationdevice (STA) 100 b may decide the best sector for the receiving arrayantenna 116 using SLS (e.g., FIG. 1 ), or may carry out a combination ofSLS and BRP. There are cases where the best sector for the transmittingarray antenna 106 and the best sector for the receiving array antenna116 are different.

FIG. 3C illustrates an example of operations of the communication device(AP) 100 a in downlink data transmission as to the communication device(STA) 100 b. The communication device (AP) 100 a sets the transmittingarray antenna 106 to the best sector with gain increased by BRP, andperforms data frame transmission. That is to say, in FIG. 3C, thecommunication device (AP) 100 a uses a beam with a narrower width thanthe beam used in FIG. 3A, so the best sector used by the communicationdevice (AP) 100 a has a higher gain and stronger directionality ascompared to the sector used in FIG. 3A. In FIG. 3C, the communicationdevice (STA) 100 b sets the receiving array antenna 116 to the bestsector, and receives data frames.

FIG. 3D illustrates an example of operations of the communication device(STA) 100 b in uplink data transmission as to the communication device(AP) 100 a. The communication device (STA) 100 b sets the transmittingarray antenna 106 to the best sector with gain increased by BRP, andperforms data frame transmission. In FIG. 3D, the communication device(STA) 100 b uses a beam with a narrower width than the beam used in FIG.3B, so the best sector used by the communication device (STA) 100 b hasa higher gain and stronger directionality as compared to the sector usedin FIG. 3B. In FIG. 3D, the communication device (AP) 100 a sets thereceiving array antenna 116 to the best sector, and receives dataframes.

Thus, in each of a case where the communication device (AP) 100 atransmits a DMG Beacon (e.g., FIG. 3A), a case where the communicationdevice (STA) 100 b transmits a response to a DMG Beacon (e.g., FIG. 3B),a case where the communication device (AP) 100 a transmits a data packet(e.g., FIG. 3C), and a case where the communication device (STA) 100 btransmits a data packet (e.g., FIG. 3D), the transmitting antenna gainand receiving antenna gain are different, so it is difficult for thecommunication device (STA) 100 b to judge whether or not a wireless linkwith the communication device (AP) 100 a can be established based on thereception power of a DMG Beacon. It is also difficult for thecommunication device (STA) 100 b to judge whether or not desired datathroughput can be realized based on the reception power of a DMG Beacon.

The Specification of U.S. Pat. No. 8,521,158 discloses a method oftransmitting a Beacon frame with EIRP and Threshold value of receptionpower included. Accordingly, in a case where the AP and STA areomni-directional, the STA can determine whether or not a wireless linkcan be established with the AP.

However, in the Specification of U.S. Pat. No. 8,521,158, noconsideration is given to the communication device (AP) 100 a switchingto the receiving q-omni antenna 115 in a case where the communicationdevice (STA) 100 b performs a sector sweep, so it is difficult in FIG.3B for the communication device (STA) 100 b to determine whether or nota wireless link can be established with the communication device (AP)100 a.

Also, in the Specification of U.S. Pat. No. 8,521,158, no considerationis given to the communication device (STA) 100 b setting the receivingarray antenna 116 to the best sector in a case where the communicationdevice (AP) 100 a performs downlink data transmission. Accordingly, in acase of the communication device (AP) 100 a performing downlink datatransmission, it is difficult for the communication device (STA) 100 bto judge whether or not predetermined data throughput can be realizedbased on reception power of DMG Beacon.

Also, in the Specification of U.S. Pat. No. 8,521,158, no considerationis given to the communication device (AP) setting the receiving arrayantenna 116 to the best sector in a case of the communication device(STA) performing transmission. Accordingly, when performing uplinktransmission, it is difficult for the communication device (STA) tojudge whether or not predetermined data throughput can be realized basedon reception power of DMG Beacon.

That is to say, even if it is difficult for the communication device(STA) 100 b to establish a wireless link with the communication device(AP) 100 a, SSW frame transmission in A-BFT is performed, so electricpower consumption increases, and unnecessary interference to other STAsoccurs.

Also, the communication device (STA) performs SSW frame transmission inA-BFT even though realization of desired data throughput is difficultwhen performing downlink and uplink data transmission, so electric powerconsumption increases, and other STAs are subjected to unnecessaryinterference.

Based on the above, it is an object of the communication deviceaccording to the embodiments of the present disclosure that will bedescribed below, to determine whether or not an SSW frame will reach acommunication device that is a communication partner in A-BFT.

First Embodiment

In a first embodiment, description will be made regarding a method ofthe communication device (STA) 100 b determining whether or not thecommunication device (AP) 100 a can receive an SSW frame in an uplinksweep, using DMG Beacon reception power, and reception gain of thequasi-omnidirectionality (quasi-omni) antenna of the communicationdevice (AP) 100 a used at the time of the uplink sector sweep includedin the DMG Beacon in a downlink sector sweep.

FIG. 4 is a diagram illustrating an example of the configuration of acommunication device 100 according to the present disclosure. Thecommunication device 100 includes a MAC control unit 101, a PHYtransmission circuit 102, a D/A converter 103, a transmission RF circuit104, a transmitting q-omni antenna 105, the transmitting array antenna106, a PHY reception circuit 112, an A/D converter 113, a reception RFcircuit 114, the receiving q-omni antenna 115, and the receiving arrayantenna 116.

The MAC control unit 101 generates transmission MAC frame data. Forexample, the MAC control unit 101 generates SSW frame data in the ISS inSLS procedures, and outputs to the PHY transmission circuit 102. The MACcontrol unit 101 also outputs control information for appropriateencoding and modulation of the generated transmission MAC frame(including header information of the PHY frame and information relatingto transmission timing) to the PHY transmission circuit 102.

The PHY transmission circuit 102 performs encoding processing andmodulation processing based on the transmission MAC frame data andcontrol information input from the MAC control unit 101, and generatesPHY frame data. The generated PHY frame is converted into analog signalsby the D/A converter 103, and is converted into wireless signals by thetransmission RF circuit 104.

The PHY transmission circuit 102 controls the transmission RF circuit104. Specifically, the PHY transmission circuit 102 performs setting ofcenter frequency in accordance with a specified channel, control oftransmission power, and control of directionality, with regard to thetransmission RF circuit 104.

The transmitting q-omni antenna 105 transmits wireless signals inputfrom the transmission RF circuit 104 as quasi-omnidirectional wirelesssignals. Note that q-omni is short for quasi-omnidirectionality(quasi-omni).

The transmitting array antenna 106 transmits wireless signals input fromthe transmission RF circuit 104 as wireless signals havingdirectionality. The transmitting array antenna 106 does not have to bean array configuration, but will be referred to as an array antenna toclarify that directionality is controlled.

The transmitting q-omni antenna 105 has a broader beam width as comparedwith the transmitting array antenna 106. On the other hand, thetransmitting array antenna 106 has a larger gain in a particulardirection as compared to other directions, in accordance with control ofdirectionality. The gain of the transmitting array antenna 106 in aparticular direction may be larger than the gain of the transmittingq-omni antenna 105.

The input power from the transmission RF circuit 104 may be greater forthe transmitting array antenna 106 as compared to the transmittingq-omni antenna 105. For example, in a case where the transmission RFcircuit 104 has a transmission amplifier for each antenna element makingup the transmitting q-omni antenna 105 and transmitting array antenna106, the transmitting array antenna 106 that has a great number ofantenna elements has a greater input power than the transmitting q-omniantenna 105 that has few antenna elements.

The communication device 100 may transmit quasi-omnidirectional wirelesssignals using the transmitting array antenna 106. That is to say, thetransmitting array antenna 106 may include the transmitting q-omniantenna 105.

For example, in the communication device 100, the transmitting arrayantenna 106 has multiple antenna elements, and the transmitting arrayantenna 106 transmits wireless signals with directionality by thetransmission RF circuit 104 being controlled so as to input power to themultiple antenna elements. Also, in the communication device 100, thetransmitting array antenna 106 transmits quasi-omnidirectional wirelesssignals by the transmission RF circuit 104 being controlled to inputpower to one or more of the multiple antenna elements of thetransmitting array antenna 106. Note that it is sufficient forquasi-omnidirectional wireless signals to use a smaller count of antennaelements than when transmitting directional wireless signals.

The receiving q-omni antenna 115 outputs wireless signals, received fromthe communication device that is a communication partner, to thereception RF circuit 114. The receiving q-omni antenna 115 hasquasi-omnidirectionality in the relationship between direction ofarrival of wireless signals and gain.

The receiving array antenna 116 outputs wireless signals to thereception RF circuit 114. The receiving array antenna 116 has strongerdirectionality than the receiving q-omni antenna 115 in the relationshipbetween direction of arrival of wireless signals and gain. The receivingarray antenna 116 does not have to be an array configuration, but willbe referred to as an array antenna to clarify that directionality iscontrolled.

The receiving q-omni antenna 115 has a broader beam width as compared tothe receiving array antenna 116. On the other hand, the receiving arrayantenna 116 has a greater gain in a particular direction as compared toother directions, in accordance with control of directionality. The gainof the receiving array antenna 116 in the particular direction may belarger than that of the receiving q-omni antenna 115.

The reception RF circuit 114 convers the wireless signals that thereceiving q-omni antenna 115 and receiving array antenna 116 havereceived into baseband signals. the A/D converter 113 converts thebaseband signals from analog signals into digital signals.

The PHY reception circuit 112 subjects the received digital basebandsignals to synchronization, channel estimation, equalization, anddemodulation, for example, to obtain reception PHY frames. Further, thePHY reception circuit 112 performs header signal analysis of thereception PHY frames and error-correction decoding, to generatereception MAC frame data.

The reception MAC frame data is input to the MAC control unit 101. TheMAC control unit 101 analyzes the contents of the reception MAC framedata, transmits the data to an upper layer (omitted from illustration),and generates transmission MAC frame data to perform responds inaccordance to the reception MAC frame data. For example, in a case ofhaving judged that the final SSW frame of ISS in SLS procedures has beenreceived, the MAC control unit 101 generates an SSW frame for RSSincluding appropriate SSW feedback information, and inputs to the PHYtransmission circuit as transmission MAC frame data.

The PHY reception circuit 112 controls the reception RF circuit 114.Specifically, the PHY reception circuit 112 performs setting of centerfrequency in accordance with a specified channel, control of receptionpower including Automatic Gain Control (AGC), and control ofdirectionality, with regard to the reception RF circuit 114.

The MAC control unit 101 also controls the PHY reception circuit 112.Specifically, the MAC control unit 101 performs starting or stopping ofreception, and starting or stopping of Carrier Sense, with regard to thePHY reception circuit 112.

FIG. 5 illustrates an example of a DMB Beacon frame that thecommunication device (AP) 100 a transmits. A DMB Beacon frame includes aFrame Body field. The Frame Body field includes an EDMG TX RX Infoelement. The EDMG TX RX Info element includes an Element ID field, aLength field, a TX EIRP field, an A-BFT RX Antenna Gain field, a BeamedTX EIRP field, and a Beamed RX Gain field. The communication device(STA) 100 b uses the EDMG TX RX Info element to judge whether or not toperform an uplink sector sweep.

The fields that the EDMG TX RX Info element includes will be describedin detail. The Element ID field includes an ID unique to the EDMG TX RXInfo element. That is to say, this is a field indicating that the FrameBody field includes the EDMG TX RX Info element.

The Length field indicates the length of the EDMG TX RX Info element inincrements of octets. In FIG. 5 , the EDMG TX RX Info element is made upof six octets, so the value of the Length field is 6.

The TX EIRP field includes an EIRP in a case where the communicationdevice (AP) 100 a is to transmit a DMG Beacon. FIG. 6 illustrates anexample of correlation between values of the TX EIRP field and values ofEIRP.

In a case where the value of the EIRP in the DMG Beacon that thecommunication device (AP) 100 a is to transmit (hereinafter, EIRP) is 0dBm or lower, the communication device (AP) 100 a sets the value of theTX EIRP field to 0. In a case where the EIRP exceeds 0 dBm but lowerthan 127 dBm, the communication device (AP) 100 a doubles the value ofthe EIRP and sets the closest integer value in the TX EIRP field. In acase where the EIRP is 127 dBm or higher, the communication device (AP)100 a sets the value of the TX EIRP field to 254. Also, in a case wherethe value of the EIRP is not to be notified to the communication device(STA) 100 b, the communication device (AP) 100 a sets the value of theTX EIRP field to 255.

The communication device (AP) 100 a may transmit each DMG Beacon at thesame EIRP. Alternatively, the communication device (AP) 100 a maytransmit each DMG Beacon at a different EIRP. For example, in thecommunication device (AP) 100 a, the EIRP changes in accordance with thedirectionality pattern by changing the directionality of thetransmitting array antenna 106. The communication device (AP) 100 aincludes the value of the EIRP in each DMG Beacon in the TX EIRP fieldof each DMG Beacon.

The communication device (AP) 100 a may transmit part of the DMG Beaconby the transmitting q-omni antenna 105, and the remainder of the DMGBeacon by the transmitting array antenna 106. In a case of thecommunication device (AP) 100 a transmitting the DMG Beacon by thetransmitting q-omni antenna 105, the value of the EIRP of thetransmitting q-omni antenna 105 is included in the TX EIRP field. TheEIRP of the transmitting q-omni antenna 105 is smaller than the EIRP ofthe transmitting array antenna 106, so the communication device (STA)100 b may reference the value of the received TX EIRP field anddistinguish whether the received DMG Beacon is a quasi-omnidirectionalwireless signal or a directional wireless signal.

The communication device (AP) 100 a may also change the transmissionpower and gain for each DMG Beacon when transmitting. The communicationdevice (AP) 100 a may set an EIRP value in accordance with thetransmission power and gain of each DMG Beacon, in the TX EIRP field ofeach DMG Beacon, and transmit. For example, the communication device(AP) 100 a may make settings whether the gain is maximum whendirectionality is controlled to the frontal direction, and the gain isseveral dB smaller as compared to the maximum gain when directionalityis controlled to a direction different from the frontal direction.

FIG. 7 illustrates a different example illustrating the correlationbetween the value of the TX EIRP field and the EIRP value. In a casewhere the accuracy of the EIRP of the communication device (AP) 100 a is1 dB, the communication device (AP) 100 a sets the value of the TX EIRPfield to one of 0 through 127. For example, in a case where the accuracyof the EIRP is 1 dB and the value of the EIRP is 3 dBm, thecommunication device (AP) 100 a sets the value of the TX EIRP field to3.

In a case where the accuracy of the EIRP of the communication device(AP) 100 a is 3 dB, the communication device (AP) 100 a sets the valueof the TX EIRP field to one of 128 through 171. For example, in a casewhere the EIRP is 6 dBm, the value of the TX EIRP field is set to 130.

The A-BFT RX Antenna Gain field includes the receiving antenna gain ofthe communication device (AP) 100 a in A-BFT, i.e., the receivingantenna gain of the receiving q-omni antenna 115.

FIG. 8 illustrates an example of the correlation between the value ofthe A-BFT RX Antenna Gain field and the value of the receiving antennagain of the communication device (AP) 100 a in A-BFT. In a case wherethe value of receiving antenna gain of the communication device (AP) 100a in A-BFT (hereinafter, receiving antenna gain) is 0 dBi or lower, thecommunication device (AP) 100 a sets the value of the A-BFT RX AntennaGain field to 0. In a case where the receiving antenna gain is more than0 dBi but less than 63.5 dBi, the communication device (AP) 100 adoubles the value of receiving antenna gain and sets the closest integervalue to the A-BFT RX Antenna Gain field. In a case where the receivingantenna gain is 63.5 dBi or grater, the communication device (AP) 100 asets the value of the A-BFT RX Antenna Gain field to 254. Also, in acase of not notifying the value of the receiving antenna gain to thecommunication device (STA) 100 b, the communication device (AP) 100 asets the value of the A-BFT RX Antenna Gain field to 255.

FIG. 9 illustrates a different example illustrating the correlationbetween the value of the A-BFT RX Antenna Gain field and the value ofthe receiving antenna gain. In a case where the accuracy of thereceiving antenna gain of the communication device (AP) 100 a is 1 dB,the communication device (AP) 100 a sets the value of the A-BFT RXAntenna Gain field to one of 0 through 63. For example, in a case wherethe accuracy of the receiving antenna gain is 1 dBi, and the receivingantenna gain is 3 dBi, the value of the A-BFT RX Antenna Gain field isset to 3.

Also, in a case where the accuracy of the reception antenna gain is 3dB, the communication device (AP) 100 a sets the value of the A-BFT RXAntenna Gain field to either 64 or 85. For example, in a case where theaccuracy of the reception antenna gain is 3 dB and the reception antennagain is 6 dBi, the value of the A-BFT RX Antenna Gain field is set to66.

Note that in A-BFT, the communication device (AP) 100 a receives SSWframes using the antenna that has the broadest beam width, so the A-BFTRX Antenna Gain field may be referred to as Wide RX Antenna Gain field.

The Beamed Tx EIRP field includes the value of the EIRP in transmissionof data packets by the communication device (AP) 100 a. That is to say,this is antenna gain used in a case where the communication device (AP)100 a controls the transmitting array antenna 106 to performtransmission by beamforming. The communication device (AP) 100 a setsthe value of the Beamed Tx EIRP field in the same way as in FIG. 6 orFIG. 7 .

The Beamed Rx Gain field includes the value of the receiving antennagain in reception of data packets by the communication device (AP) 100a. That is to say, this is antenna gain used in a case of thecommunication device (AP) 100 a controlling the receiving array antenna116 and performing reception by beamforming. The communication device(AP) 100 a sets the value of the Beamed Rx Gain field in the same way asin FIG. 8 or FIG. 9 .

FIG. 10 illustrates an example of reception processing of the DMG Beaconframe in FIG. 5 by the communication device (STA) 100 b. Thecommunication device (STA) 100 b judges whether or not connection can bemade to the communication device (AP) 100 a in an uplink sector sweep,by performing reception processing of a DMG Beacon frame.

In step S101, the communication device (STA) 100 b receives a DMG Beaconframe and measures the reception power. The communication device (STA)100 b may convert the reception power into RSSI (Receive signal strengthindicator). Hereinafter, the converted reception power will be writtenas RSSI_Beacon (in units of dBm).

Note that in step S101, in a case where the communication device (STA)100 b has received multiple DMG Beacon frames, the reception power ofthe DMG Beacon frame of which the reception quality is best is set asthe RSSI_Beacon.

Also, the value of the EIRP, where the value of the TX EIRP field of theDMG Beacon frame received by the communication device (STA) 100 b hasbeen converted using FIG. 6 or FIG. 7 , is set as EIRP Beacon (in unitsof dBm).

Also, the value of the receiving antenna gain, where the value of theA-BFT RX Antenna Gain field of the DMG Beacon frame received by thecommunication device (STA) 100 b has been converted using FIG. 8 or FIG.9 , is set as RxGain ABFT (in units of dBi).

Also, the value of the EIRP, where the value of the Beamed Tx EIRP fieldof the DMG Beacon frame received by the communication device (STA) 100 bhas been converted using FIG. 6 or FIG. 7 , is set as EIRP AP Data (inunits of dBm).

Also, the value of the receiving antenna gain, where the value of theBeamed RX Gain field of the DMG Beacon frame received by thecommunication device (STA) 100 b has been converted using FIG. 8 or FIG.9 , is set as RxGain AP Data (in units of dBm).

In step S102, the communication device (STA) 100 b uses Expression 1 tocalculate loss on the propagation channel (hereinafter referred in asPathLoss_Beacon (in increments of dB)) in FIG. 3A.

PathLoss_Beacon=EIRP Beacon+RxGain_Beacon−RSSI_Beacon   (1)

In Expression 1, RxGain_Beacon is the receiving antenna gain of thecommunication device (STA) 100 b in FIG. 3A (i.e., gain of the receivingq-omni antenna).

In step S103, the communication device (STA) 100 b uses Expression 2 toestimate the power (referred to as RSSI_ABFT, in units of dBm) of thecommunication device (AP) 100 a receiving an SSW frame in FIG. 3B (i.e.,A-BFT).

RSSI_ABFT=EIRP_ABFT−PathLoss_Beacon+RxGain_ABFT   (2)

Now, EIRP_ABFT (in units of dBm) is an EIRP at which the communicationdevice (STA) 100 b transmits SSW frames in A-BFT. The communicationdevice (STA) 100 b assumes that the losses of the propagation channelsin FIGS. 3A and 3B are equal.

In a case where the value of the RSSI_ABFT calculated in step S103exceeds the value of the sensitivity level, the communication device(STA) 100 b transmits an SSW frame in A-BFT (step S105). The value ofthe sensitivity level is a specification requesting reception power thatis determined corresponding to the Modulation and Coding Scheme (MCS)used in transmission of SSW frames in A-BFT. For example, in the 11adstandard, the sensitivity level for MCSO is −78 dBm.

In a case where case where the value of the RSSI_ABFT calculated in stepS103 does not exceed the value of the sensitivity level (No in stepS104), the communication device (STA) 100 b does not transmit an SSWframe in A-BFT, and the processing ends. In this case, the communicationdevice (STA) 100 b may transition to a standby state to receive a DMGBeacon frame from another communication device (AP) 100 c, or maytransition to step S101.

Note that in a case where a value obtained by adding estimated loss tothe value of the RSSI_ABFT calculated in step S103 exceeds the value ofthe sensitivity level (Yes in step S104), the communication device (STA)100 b may transmit an SSW frame in A-BFT in step S105. The communicationdevice (STA) 100 b may determine an estimation error in accordance witherror occurring in measurement of reception power in step S101. Theestimation error is 3 dB, for example.

Also, the communication device (STA) 100 b may determine the estimationerror by adding the accuracy of the EIRP Beacon illustrated in FIG. 7 ,and the RxGain_ABFT illustrated in FIG. 9 , to the measurement accuracyof reception power in step S101. For example, in a case where themeasurement accuracy of reception power is 3 dB, the value of the TXEIRP field of the DMG Beacon is 131 (i.e., the accuracy of the value ofthe EIRP is 3 dB), and the value of the A-BFT RX Antenna Gain field ofthe DMG Beacon is 40 (i.e., the accuracy of the value of the gain is 1dB), the measurement error may be determined to be 7 dB (3 dB+3 dB+1dB).

The communication device (STA) 100 b may also repeat step S101 throughstep S103 for multiple APs (communication device (AP) 100 a andcommunication device (AP) 100 c), and estimate the reception power instep S103 for each AP. The communication device (STA) 100 b may performthe processing of steps S104 and S105 for the AP of which the estimatedreception power is the greatest.

In a case where a wireless link with a PCP/AP (communication device (AP)10 c) other than the communication device (AP) 100 a that hastransmitted the DMG Beacon in step S101 has already been established,the communication device (STA) 100 b may perform the processing of thesteps with regard to the communication device (AP) 100 a in a case wherethe power of the DMG Beacon measured in step S101 is greater than thereception power of the DMG Beacon received from the communication device(AP) 100 c.

In a case of making judgement of No in step S104, SSW frames that thecommunication device (STA) 100 b transmits do not reach thecommunication device (AP) 100 a, so the communication device (STA) 100 bdoes not perform transmission of an SSW frame to the communicationdevice (AP) 100 a (step S105) to the communication device (AP) 100 a,and connection with the communication device (AP) 100 c is continued.

In a case of making judgement of Yes in step S104, SSW frames that thecommunication device (STA) 100 b transmits reach the communicationdevice (AP) 100 a, so the communication device (STA) 100 b performstransmission of an SSW frame to the communication device (AP) 100 a(step S105) to the communication device (AP) 100 a.

In this case, the communication device (STA) 100 b may transmit a framenotifying the communication device (AP) 100 c of separation (e.g., aDisassociation frame) after step S105, and transmit a frame notifyingthe communication device (AP) 100 a of connection (e.g., an Associationframe). Accordingly, the communication device (STA) 100 b can select andconnect to an AP with better reception quality.

FIG. 11 illustrates a different example of reception processing of theDMG Beacon frame illustrated in FIG. 5 by the communication device (STA)100 b. Steps that are the same as in FIG. 10 are denoted by the samenumerals, and description will be omitted.

In step S104, in a case where case where the value of the RSSI_ABFTcalculated in step S103 does not exceed the value of the sensitivitylevel (No in step S104), the communication device (STA) 100 b does notperform transmission of an SSW in A-BFT (step S108), and endsprocessing.

In step S104, in a case where the value of the RSSI_ABFT calculated instep S103 exceeds the value of the sensitivity level (Yes in step S104),the communication device (STA) 100 b calculates the estimation value ofreception power of data packets received by the communication device(STA) 100 b in FIG. 3C (called RSSI_STA_Data) using Expression 3 (stepS106).

RSSI_STA_Data=EIRP_AP_Data−PathLoss_Beacon+RxGain_STA_Data   (3)

In Expression 3, RxGain STA Data is reception antenna gain of thecommunication device (STA) 100 b in FIG. 3C, i.e., reception antennagain in a case where the communication device (STA) 100 b has set thereceiving array antenna 116 to the best sector. Also, the communicationdevice (STA) 100 b assumes that the losses of the propagation channelsin FIGS. 3A and 3C are equal in Expression 3.

In step S107, the communication device (STA) 100 b determines whether ornot desired throughput can be obtained in downlink data communication,based on the value of RxGain STA Data.

FIG. 12A illustrates an example of values of reception sensitivity level(Receive sensitivity) as to MCS in the 11ad standard. FIG. 12Billustrates an example of maximum throughput values as to MCS in the11ad standard.

For example, the communication device (STA) 100 b compares the value ofRxGain STA Data and the value of the reception sensitivity level as toMCS in the 11ad standard that is illustrated in FIG. 12A, and decidesthe greatest MCS capable of reception. For example, in a case where thevalue of RxGain_STA_Data is −60 dBm, the MCS that has a receptionsensitivity level smaller than the value of RxGain_STA_Data is MCS8.That is to say, the largest MCA that the communication device (STA) 100b can receive in FIG. 3C is 8.

The communication device (STA) 100 b may also calculate the greatestthroughput that can be received, based on the maximum throughput valuesas to MCS in the 11ad standard illustrated in FIG. 12B. For example, ina case where the RxGain_STA_Data is −60 dBm, the greatest MCS that thecommunication device (STA) 100 b can receive is 8, so the greatestthroughput is 2310 Mbps.

In a case where the greatest MCS that can be received, calculated instep S106, is a value decided beforehand or greater (Yes in step S107),the communication device (STA) 100 b transmits an SSW frame in A-BFT(step S108). On the other hand, in a case where the greatest MCS thatcan be received, calculated in step S106, is smaller than the valuedecided beforehand (No in step S107), the communication device (STA) 100b does not transmit an SSW frame in A-BFT (step S108), and theprocessing ends.

Also, in a case where the maximum throughput that can be received,calculated in step S106, is a value decided beforehand or greater (Yesin step S107), the communication device (STA) 100 b transmits an SSWframe in A-BFT (step S108). On the other hand, in a case where themaximum throughput that can be received, calculated in step S106, issmaller than the value decided beforehand (No in step S107), thecommunication device (STA) 100 b does not transmit an SSW frame in A-BFT(step S108), and the processing ends.

Also, in a case where the communication device (STA) 100 b has alreadyestablished a wireless link with a different PCP/AP than thecommunication device (AP) 100 a that has transmitted the DMG Beacon instep S101 (hereinafter, referred to as different PCP/AP), thecommunication device (STA) 100 b transmits an SSW frame in step S108 ina case where the greatest MCS that can be received, calculated in stepS106, is greater than the MCS that can be used with the different PCP/AP(Yes in step S107). On the other hand, in a case where the greatest MCSthat can be received, calculated in step S106, is equal to or less thanthe MCS that can be used with the different PCP/AP (Yes in step S107),the communication device (STA) 100 b does not transmit an SSW frame inA-BFT (step S108), and ends processing.

In this case, the communication device (STA) 100 b may transmit a framenotifying the different PCP/AP of separation (e.g., a Disassociationframe) after step S108, and transmit a frame notifying the communicationdevice (AP) 100 a of connection (e.g., an Association frame).Accordingly, the communication device (STA) 100 b can select and connectto an PCP/AP with better reception quality.

Also, the communication device (STA) 100 b may compare a value whereestimation error has been subtracted from the RxGain STA Data value, andthe value of reception sensitivity level in FIG. 12A. Accordingly, thecommunication device (STA) 100 b can avoid repeated disconnection andconnection among multiple PCP/APs having equivalent throughput.

Also, in a case of having a different communication arrangement from the11ad standard (e.g., 5 GHz Wi-Fi-communication, IEEE 802.11ac standard,etc.) the communication device (STA) 100 b may transmit an SSW frame inA-BFT in a case where the maximum throughput that can be received,calculated in step S106, exceeds throughput in the differentcommunication arrangement.

Note that in a case where the value of RSSI_ABFT calculated in step S103exceeds the value of the sensitivity level (Yes in step S104), thecommunication device (STA) 100 b may calculate the estimation value ofreception power of data packets received by the communication device(AP) 100 a in FIG. 3D (called RSSI_AP_Data) using Expression 4.

RSSI_AP_Data=EIRP_STA_Data−PathLoss_Beacon+RxGain_AP_Data   (4)

In Expression 4, EIRP STA Data is transmission antenna gain of thecommunication device (STA) 100 b in FIG. 3D, i.e., EIRP in a case wherethe communication device (STA) 100 b has set the transmitting arrayantenna 106 to the best sector. Also, the communication device (STA) 100b assumes that the losses of the propagation channels in FIGS. 3A and 3Dare equal in Expression 4.

In step S107, the communication device (STA) 100 b determines whether ornot desired throughput can be obtained in uplink data communication,based on the value of RxGain_AP_Data. The communication device (STA) 100b may calculate the greatest MCS that the communication device (AP) 100a can receive, and calculate a realizable throughput, as describedregarding downlink data communication.

In a case where the greatest MCS that the communication device (AP) 100a can receive, calculated in step S106, is equal to or greater than avalue decided beforehand (Yes in step S107), the communication device(STA) 100 b transmits an SSW frame in A-BFT (step S108).

Also, in a case where the throughput that can be realized in uplink datacommunication, calculated in step S106, is equal to or greater than avalue decided beforehand (Yes in step S107), the communication device(STA) 100 b transmits an SSW frame in A-BFT (step S108).

Note that an arrangement may be made where, in a case where thethroughput that can be realized in both downlink and uplink datacommunication is equal to or greater than a value decided beforehand(Yes in step S107), the communication device (STA) 100 b transmits anSSW frame in A-BFT (step S108).

Also note that the communication device (AP) 100 a may performnotification of information relating to the EDMG TX RX Info elementusing a communication format other than millimeter wave communication(11ad and 11ay).

Note that the communication device (AP) 100 a may include informationregarding the MIMO stream count in the DMG Beacon and transmit, in stepS101 in FIG. 11 . The communication device (STA) 100 b calculates arealizable MIMO stream from information of MIMO stream count of thecommunication device (AP) 100 a included in the DMG Beacon, andinformation of the MIMO stream count of the communication device (STA)100 b. For example, the communication device (STA) 100 b may select thesmaller figure regarding MIMO streams of the communication device (AP)100 a and communication device (STA) 100 b.

In step S107 in FIG. 11 , the communication device (STA) 100 b maymultiply the calculated realizable throughput by the value of realizableMIMO streams, and calculate the realizable throughput in MIMO. Thecommunication device (STA) 100 b may use the value of realizablethroughput in MIMO to determine whether the desired downlink throughputcan be obtained.

Also, in a case of calculating realizable throughput in MIMO, thecommunication device (STA) 100 b may subtract a value corresponding tothe MIMO stream count, from the reception power of data framescalculated using Expression 3, in step S106 FIG. 11 . For example, in acase where the MIMO stream count is two, the communication device (STA)100 b may subtract 3 dB from the calculated reception power, deeming thepower to be dispersed among two streams.

Note that in step S101 in FIG. 11 , the communication device (AP) 100 amay transmit the information in the DMG Beacon, including information ofthe channel count regarding channel bonding and channel aggregationtherein.

The communication device (STA) 100 b may calculate realizable throughputin channel bonding and channel aggregation in the same way as with MIMO.That is to say, the communication device (STA) 100 b may multiply thevalue of realizable throughput by the channel count. The calculatedreception power may also be adjusted in accordance with the channelcount. For example, subtracting 3 dB in a case of two channels, andsubtracting 6 dB in a case of four channels, may be performed.

Although an example has been described in the present embodimentregarding a case where the communication device (AP) 100 a transmits aDMG Beacon and the communication device (STA) 100 b transmits an SSWframe in A-BFT, the communication device (STA) 100 b may transmit a DMGBeacon and the communication device (AP) 100 a transmit an SSW frame inA-BFT.

As described above, in the first embodiment, the communication device(AP) 100 a transmits a DMG Beacon frame including the TX EIRP field andA-BFT RX Antenna Gain field, so judgment can be made at thecommunication device (STA) 100 b regarding whether or not an SSW framein A-BFT will reach the communication device (AP) 100 a. Accordingly,transmission of unnecessary SSW frames can be avoided, so electric powerconsumption of the communication device (STA) 100 b can be reduced, andoccurrence of unnecessary interference waves to other STAs can bereduced.

Also, in the first embodiment, the communication device (AP) 100 atransmits a DMG Beacon frame including the TX EIRP field, A-BFT RXAntenna Gain field, Beamed TX EIRP field, and Beamed RX gain field, sojudgment can be made at the communication device (STA) 100 b regardingwhether or not communication at a desired data throughput can berealized. Accordingly, transmission of unnecessary SSW frames can beavoided, so electric power consumption of the communication device (STA)100 b can be reduced, and occurrence of unnecessary interference wavesto other STAs can be reduced.

Also, in the first embodiment, the communication device (AP) 100 atransmits a DMG Beacon frame including the TX EIRP field, A-BFT RXAntenna Gain field, Beamed TX EIRP field, and Beamed RX gain field, sodata throughput can be estimated at the communication device (STA) 100b, and accordingly the PCP/AP and communication format with the highestdata throughput can be selected.

Second Embodiment

Although an arrangement has been described in the first embodiment wherea DMG Beacon frame is transmitted including the TX EIRP field, A-BFT RXAntenna Gain field, Beamed TX EIRP field, and Beamed RX gain field, acase will be described in a second embodiment regarding an arrangementwhere a DMG Beacon frame is transmitted including the TX EIRP field andA-BFT RX Antenna Gain field, and further, a Probe Request frame istransmitted including the Beamed TX EIRP field and Beamed RX gain field.

FIG. 13 is a diagram illustrating an example of procedures forperforming communication between the communication device (AP) 100 a(hereinafter, AP1) and the communication device (STA) 100 b(hereinafter, STA1).

In step S201, the AP1 changes sectors and transmits each DMG Beaconframe in each sector. FIG. 14 illustrates an example of the format of aDMG Beacon frame. The DMG Beacon frame in FIG. 14 includes an SSW fieldin a Frame Body. The SSW field includes a TX EIRP field and A-BFT RXAntenna Gain field.

The TX EIRP field and A-BFT RX Antenna Gain field in FIG. 14 are used inthe same way as in FIG. 5 , but the bit count differs from FIG. 5 . FIG.15 illustrates an example of TX EIRP field values. The TX EIRP field isfour bits, and the values are in 5 dB increments. FIG. 16 illustrates anexample of values of the A-BFT RX Antenna Gain field. The A-BFT RXAntenna Gain field is two bits, and the values are in 5 dB increments.Note that in a case where the value of A-BFT RX Antenna Gain isundetermined, the AP1 may set the value of the A-BFT RX Antenna Gainfield to 0 (i.e., the smallest value of A-BFT RX Antenna Gain field).

In step S202, the STA1 estimates the power (RSSI_ABFT) of thecommunication device (AP) 100 a receiving an SSW frame in FIG. 3B (i.e.,A-BFT), using the TX EIRP value and A-BFT RX Antenna Gain value receivedin step S201, using Expression 1 and Expression 2.

In a case where the value of the RSSI_ABFT is equal to or greater thansensitivity level of the SSW frame in A-BFT (e.g., −78 dBm which is thesensitivity level of MCSO in the 11ad standard), the STA1 transmits anSSW frame in A-BFT.

The AP1 receives the SSW frame in step S202, and in step S203 transmitsan SSW-FB frame.

In step S204, the STA1 transmits a Probe Request frame, and requests aProbe Response frame from the API.

In step S205, the AP1 transmits a Probe Response frame. FIG. 17illustrates an example of a Probe Response frame.

The Probe Response frame includes information necessary for the STA1 toconnect (association) the AP1. Included, for example, are an Service setidentifier (SSID) field and a DMB Capabilities field. The EDMG TX RXInfo field is also included. The configuration of the EDMG TX RX Infofield is the same as that in the first embodiment (see FIG. 5 ).

In step S205, the STA1 calculates the values of RSSI_STA_Data andRSSI_AP_Data using the same procedures as step S106 in FIG. 11 andExpression 3 and Expression 4, and determines whether or not desireddata throughput is realizable with regard to the AP1.

In a case of having determined that the desired data throughput isrealizable, the STA1 transmits an Association Request to the AP1, andperforms association. After having performed association regarding theAP1, the STA1 may use SLS and BRP to perform beamforming training of thereceiving array antenna. Also, after having performed associationregarding the AP1, the STA1 may use SLS and BRP to perform high-accuracybeamforming training of the transmitting array antenna. That is to say,the STA1 further narrows the beam width in comparison with the sectorused in step S202 (A-BFT) to raise gain, and performs SLS and BRP (stepS206).

Also, after the STA1 has performed association regarding the AP1, theAP1 may use SLS and BRP to perform beamforming training of the receivingarray antenna and high-accuracy beamforming training of the transmittingarray antenna. That is to say, the AP1 further narrows the beam width incomparison with the sector used in step S201 (transmission of DMGBeacon) to raise gain, and performs SLS and BRP.

In a case of judging that the desired data throughput is not realizable,the STA1 does not transmit an Association Request frame to the AP1. Inthis case, the STA1 may standby for a DMG Beacon from another AP (e.g.,AP2), and receive (step S201A).

In a case of having received a DMG Beacon from another AP in step S201A,the STA1 may perform the processing of step S202 and hereafter withregard to the other AP.

In this way, the STA1 avoids connection with an AP regarding which thedesired throughput is not realizable (e.g., AP1), and performs A-BFTregarding an AP regarding which the desired throughput is realizable(e.g., AP2), so connection with an suitable AP can be realized.

The AP1 transmits a DMG Beacon frame, SSW-FB frame, and Probe Responseframe, in steps S201, S203, and S205, at the same EIRP. The STA1receives the DMG Beacon frame, SSW-FB frame, and Probe Response frame,in steps S201, S203, and S205, using the receiving q-omni antenna 115(see FIG. 3A). That is to say, the EIRP of the AP1 and the receptionantenna gain of the STA1 differ from that in downlink data communication(see FIG. 3C). Accordingly, it is difficult for the STA1 to estimatedata throughput based on reception power of the DMG Beacon frame, SSW-FBframe, and Probe Response frame.

On the other hand, the communication device (AP) 100 a according to thesecond embodiment transmits the DMG Beacon frame including the TX EIRPfield and A-BFT RX Antenna Gain field, and transmits the Probe Requestframe including the Beamed TX EIRP field and Beamed RX gain field, sothe communication device (STA) 100 b can judge whether the desiredthroughput can be realized before association, and can connect with asuitable AP.

The communication device (AP) 100 a according to the second embodimenttransmits the DMG Beacon frame including the TX EIRP field and A-BFT RXAntenna Gain field, and transmits the Probe Request frame including theBeamed TX EIRP field and Beamed RX gain field, so the DMG Beacon framecan be made shorter as compared to the first embodiment.

The communication device (AP) 100 a transmits multiple DMG Beacon frameswhile changing sectors, so shortening the DMG Beacon frame enablesreduction of the amount of time to connect to a STA, and reduction ofinterference to other STAs.

Modification of Second Embodiment

Although the value of the TX EIRP and the value of the A-BFT RX AntennaGain are each transmitted in a DMG Beacon frame in the secondembodiment, a difference between the value of the TX EIRP field and thevalue of the A-BFT RX Antenna Gain is transmitted in a modification ofthe second embodiment.

FIG. 18 illustrates a different example of the format of the DMG Beaconframe. The DMG Beacon frame in FIG. 18 includes the SSW field in theFrame Body, and includes the Differential Gain field in the SSW field.

FIG. 19 illustrates an example of the value of the Differential Gainfield. The value of Differential Gain (DIFF_Gain_Beacon) represents thedifference between the value of the TX EIRP and the value of the A-BFTRX Antenna Gain, and is calculated by Expression 5.

DIFF_Gain_Beacon=EIRP_Beacon−RxGain_ABFT   (5)

The AP1 decides the value of the Differential Gain field in accordancewith the accuracy of the value of Differential Gain and the valuecalculated in Expression 5 using FIG. 19 . For example, in a case wherethe accuracy of Differential Gain is 3 dB, and the value of DifferentialGain calculated by Expression 5 is 9 dB, the value of the DifferentialGain field is 3. Note that in a case of having received the DMG Beaconin FIG. 14 , the STA1 may calculate the value of DIFF_Gain_Beacon usingExpression 5.

In step S201 in FIG. 13 , the STA1 estimates the power (RSSI_ABFI) ofthe communication device (AP) 100 a receiving an SSW frame in FIG. 3B(i.e., A-BFT) using the value of the Differential Gain that has beenreceived, using Expression 6 that is a combination of Expression 1,Expression 2, and Expression 5.

-   -   RSSI_ABFT

=EIRP_ABFT−PathLoss_Beacon+RxGain_ABFT

=EIRP_ABFT−(EIRP_Beacon+RxGain_Beacon−RSSI_Beacon)+RxGain ABFT

=RSSI_Beacon+EIRP_ABFT−RxGain_Beacon−(EIRP_Beacon−RxGain_ABFT)

=RSSI_Beacon+EIRP_ABFT−RxGain_Beacon−DIFF_Gain_Beacon   (6)

In Expression 6, RSSI_Beacon is the reception power strength of the DMGBeacon that the STA1 measures in step S201 in FIG. 13 . Also,RxGain_Beacon is the antenna gain at the STA1 at the time of receivingthe DMG Beacon frame, and EIRP_ABFT is the transmission EIRP of the STA1at the time of A-BFT. That is to say, the STA1 receives the value ofDIFF_Gain_Beacon in step S201 in FIG. 13 , and accordingly can calculatethe value of RSSI_ABFT using Expression 6. Accordingly, the STA1 candistinguish whether or not an SSW frame will reach the AP1, beforeperforming SSW frame transmission in step S202 in FIG. 13 .

FIG. 20 illustrates a different example of a format of a Probe Responseframe. The Probe Response frame illustrated in FIG. 20 includes aRelative Beamed TX EIRP field and Relative Beamed Rx Gain field, unlikethat in FIG. 17 .

The Relative Beamed TX EIRP field represents the difference between thevalue of EIRP_AP_Data and the value of EIRP_Beacon, determined inExpression 7 (hereinafter written as EIRP_AP_Relative).

EIRP_AP_Relative=EIRP_AP_Data−EIRP_Beacon   (7)

FIG. 21 illustrates an example of values of the Relative Beamed TX EIRPfield. The communication device (AP) 100 a selects the values of theRelative Beamed TX EIRP field in accordance with the value ofEIRP_AP_Relative and the accuracy, in the same way as in FIGS. 9 and 18.

The Relative Beamed Rx Gain field represents the difference between thevalue of RxGain_AP_Data and the value of RxGain_ABFT determined inExpression 8 (hereinafter written as RxGain_AP_Relative).

RxGain_AP_Relative=RxGain_AP_Data−RxGain_ABFT   (8)

The communication device (AP) 100 a selects the value of the RelativeBeamed Rx Gain field in accordance with the value of EIRP AP Relativeand the accuracy, in the same way as with the Relative Beamed Tx EIRPfield (see FIG. 21 ).

In step S205 in FIG. 13 , the STA1 calculates the value of RSSI_STA_Datausing Expression 9, and determines whether or not the desired MCS anddata throughput can be realized in a down data link (FIG. 3C).

RSSI_STA_Data

=EIRP_AP_Data−PathLoss_Beacon+RxGain_STA_Data

=EIRP_AP_Data−(EIRP_Beacon+RxGain_Beacon−RSSI_Beacon)+RxGain_STA_Data

=RSSI_Beacon+(EIRP_AP_Data−EIRP_Beacon)+(RxGain_STA_Data−RxGain_Beacon)

=RSSI_Beacon+EIRP_AP_Relative+(RxGain_STA_Data−RxGain_Beacon)   (9)

In Expression 9, RSSI_Beacon is the reception power strength of the DMGBeacon that the STA1 has measured in step S201 in FIG. 13 .RxGain_Beacon is the antenna gain of the STA1 at the time of receivingthe DMG Beacon frame, and RxGain_STA_Data is the reception antenna gainof the STA1 at the time of data communication. That is to say, the STA1receives the value of EIRP_AP_Relative in step S205, so the value ofRSSI_STA_Data can be calculated using Expression 9.

In step S205 in FIG. 13 , the STA1 may calculate the value ofRSSI_AP_Data using Expression 10, and determine whether or not thedesired MCS and data throughput can be realized in an up data link (FIG.3D).

RSSI_AP_Data

=EIRP_STA_Data−PathLoss_Beacon+RxGain_AP_Data

=EIRP_STA_Data−(EIRP_Beacon+RxGain_Beacon−RSSI_Beacon)+RxGain_AP_Data

=RSSI_Beacon−(EIRP_Beacon−RxGain_AP_Data)+(EIRP_STA_Data−RSSI_Beacon)

=RSSI_Beacon+(RxGain_STA_Data−RxGain_Beacon)−(DIFF_Gain_Beacon+RxGain_ABFT−RxGain_AP_Relative−RxGain_ABFT)

=RSSI_Beacon+(RxGain_STA_Data−RxGain_Beacon)(DIFF_Gain_Beacon−RxGain_AP_Relative)  (10)

In Expression 10, RSSI_Beacon is the reception power strength of the DMGBeacon that the STA1 has measured in step S201 in FIG. 13 . RxGainBeacon is the antenna gain of the STA1 at the time of receiving the DMGBeacon frame, and RxGain_STA_Data is the reception antenna gain of theSTA1 at the time of data communication. That is to say, the STA1receives the value of DIFF Gain Beacon in step S201 in FIG. 13 , andreceives the value of RxGain_AP_Relative in step S205, so the value ofRSSI_AP_Data can be calculated using Expression 10.

Note that in the present embodiment, description has been made regardingan example of a case where the communication device (AP) 100 a transmitsDMG Beacon and Probe Response frames including information related toantenna gain, but this is the same for a case of the communicationdevice (STA) 100 b transmitting a DMG Beacon. In this case, thetransmission direction of frames in steps S201, S202 and S203 in FIG. 13is reverse, and in step S201, the communication device (STA) 100 btransmits the DMG Beacon frame in FIG. 14 . Also, unlike FIG. 13 , thecommunication device (STA) 100 b transmits the Probe Request frame instep S204 with the EDMG TX RX Info element (see FIG. 17 ) included.

The communication device (AP) 100 a uses the value included in the EDMGTX RX Info element to calculate the realizable throughput, anddetermines whether or not the desired throughput is realizable. If notrealizable, the communication device (AP) 100 a transmits an AssociationResponse including a field (e.g., status code) notifying non-permissionof association, after having received the Association Request in stepS206.

Also, the communication device (AP) 100 a may notify a control devicethat is omitted from illustration of the calculated realizablethroughput. The control device receives the value of the realizablethroughput relating to the communication device (STA) 100 b frommultiple APs (e.g., communication device (AP) 100 a and communicationdevice (AP) 100 c), and transmits a signal recommending association withthe communication device (STA) 100 b to the AP with the highest value(e.g., communication device (AP) 100 a). Also, the address of an APregarding which association with the communication device (STA) 100 b isrecommended (e.g., address of communication device (AP) 100 a) may benotified to multiple APs.

For example, in a case of having received a signal recommendingassociation with the communication device (STA) 100 b, the communicationdevice (AP) 100 a may transmit an Association Response to the STA1 andpermit association with the STA1, upon having received an AssociationRequest in step S206 in FIG. 13 .

Also, in a case of having not received a signal recommending associationwith the communication device (STA) 100 b, the communication device (AP)100 a may transmit an Association Response to the STA1 including a fieldnotifying non-permission of association (e.g., status code), upon havingreceived an Association Request in step S206 in FIG. 13 .

The communication device (AP) 100 a may in step S205 transmit a ProbeResponse frame to the communication device (STA) 100 b including theaddress of the AP regarding which association with the communicationdevice (STA) 100 b is recommended, that has been notified by the controldevice.

The communication device (AP) 100 a may change the transmission powerand gain for each DMG Beacon when transmitting. The communication device(AP) 100 a may set the value of Differential Gain in accordance with thetransmission power and gain, and gain of receiving q-omni antenna 115,of each DMG Beacon, in the Differential Gain field of each DMG Beacon,and transmit. For example, the communication device (AP) 100 a may makesettings whether the gain is maximum when directionality of thetransmitting array antenna 106 is controlled to the frontal direction,and the gain is several dB smaller as compared to the maximum gain whendirectionality is controlled to a direction different from the frontaldirection.

Also, the communication device (AP) 100 a may have gain where the gainof the receiving q-omni antenna 115 differs in accordance with thedirection of arrival of wireless signals. The communication device (AP)100 a may set the value of the transmitting EIRP, and the value ofDifferential Gain in accordance with the value of gain of the receivingq-omni antenna 115 corresponding to the transmission direction of eachDMG Beacon frame, in the Differential Gain field of each DMG Beacon.Thus, the communication device (STA) 100 b can associate with the APthat has the best communication quality.

The communication device (AP) 100 a according to the modification of thesecond embodiment transmits DMG Beacon frames including the DIFF GainBeacon field, and transmits Probe Request frames including the RelativeBeamed Tx EIRP field and Relative Beamed Rx Gain field, so thecommunication device (STA) 100 b can judge whether or not desiredthroughput can be realized before association, and connection with asuitable AP can be made.

The communication device (AP) 100 a according to the modification of thesecond embodiment transmits DMG Beacon frames including the DIFF GainBeacon field, and transmits Probe Request frames including the RelativeBeamed Tx EIRP field and Relative Beamed Rx Gain field, so the DMGBeacon frame fan be made shorter as compared to the first embodiment.

The communication device (AP) 100 a transmits the DMG Beacon frames ineach sector while changing sectors, so shortening the DMG Beacon framecan reduce time necessary to connect to a STA, and reduce interferenceas to other STAs.

Third Embodiment

Although the communication device (STA) 100 b determines whether or notto transmit an SSW frame based on a DMG Beacon frame received from onecommunication device (AP) 100 a in the first embodiment and secondembodiment, the communication device (STA) 100 b determines whether ornot to transmit an SSW frame based on a DMG Beacon frame received frommultiple communication devices (AP) 100 a in a third embodiment.

FIG. 22 is a diagram illustrating an example of procedures forcommunication between the communication device (AP) 100 a (hereinafter,AP1) and communication device (STA) 100 b (hereinafter, STA1).

In step S301, the AP1 transmits a DMG Beacon frame with a NeighborReport element included therein. Note that the STA1 has alreadycompleted association with the AP1 before step S301.

FIG. 23 illustrates an example of the format of a DMG Beacon frame. TheNeighbor Report element includes information of APs present nearby theAP1 (e.g., AP2), that the AP1 has detected. In the DMG Beacon frame, theAP1 includes an EDMG TX RX Info field in an Optional Subelements portionof the Neighbor Report element and transmits.

The EDMG TX RX Info field in FIG. 23 is equivalent to the fields of theEDMG TX RX Info element in FIG. 5 (first embodiment) from which thestart Element ID field and Length field have been removed. That is tosay, the EDMG TX RX Info field includes the TX EIRP field, A-BFT RXAntenna Gain field, Beamed TX EIRP field, and Beamed RX gain field. Theway to determine the values of these fields is as illustrated in thefirst embodiment.

However, while information relating to the AP1 is included in the valueof the EDMG TX RX Info field in FIG. 5 in the first embodiment,information relating to the AP2 is included in FIG. 23 . That is to say,the TX EIRP field in FIG. 23 includes the value of EIRP_Beacon of theAP2, and the A-BFT RX Antenna Gain field includes the value ofRxGain_ABFT of the AP2.

The AP2 notifies the AP1 of the values of the TX EIRP field, A-BFT RXAntenna Gain field, Beamed TX EIRP field, and Beamed RX gain field,relating to the AP2 before step S301.

In step S302, the STA1 receives the DMG Beacon frame that the AP2 hastransmitted. Note that the AP2 does not have to include the EDMG TX RXInfo field in the DMG Beacon, so as to shorten the length of the DMGBeacon frame.

The STA1 judges whether or not an SSW frame in A-BFT will reach the AP2,based on Expression 1 and Expression 2, using the value of the EDMG TXRX Info field of the AP2 included in the Neighbor Report in step S301.Also, the STA1 judges whether or not the desired data throughput can berealized in uplink and downlink data communication with the AP2, e.g.,whether or not data throughput exceeding that in data communication withthe AP1 can be exceeded, based on Expression 1 and Expression 2.

In a case of having judged that an SSW frame can reach the AP2 in A-BFT,and the desired data throughput can be realized with downlink and uplinkdata communication with the AP2, the STA1 transmits an SSW frame inA-BFT to the AP2 (step S303).

In a case of having judged that an SSW frame cannot reach the AP2 inA-BFT, or that it will be difficult to realize the desired datathroughput with downlink and uplink data communication with the AP2, theSTA1 does not transmit an SSW frame in A-BFT to the AP2. In this case,the STA1 may maintain association with the AP1, and communicate with theAP1 (step S304).

The AP1 may periodically include a Neighbor Report in the DMG Beaconframe. For example, the AP1 may include a Neighbor Report once every tenbeacon intervals. That is to say, the AP1 does not include a NeighborReport in the DMG Beacon for nine beacon intervals, and includes aNeighbor Report in all DMG Beacons during the BTI period. Accordingly,the amount of time necessary to transmit a DMG Beacon frame can bereduced, and interference as to other STAs can be reduced.

The STA1 has association with the AP1, and accordingly receives the DMGBeacon frame each time. Accordingly, even in cases where a NeighborReport is periodically included in the DMG Beacon frames, the STA1 canreceive DMG Beacons including a Neighbor Report.

The STA1 can store the received Neighbor Report, and use the value ofthe EDMG TX RX Info field of the AP2 included in the Neighbor Report, asnecessary. Accordingly, in a case of having received a DMG Beacon fromthe AP2 in step S302, the STA2 can perform calculation of Expression 1through Expression 4, and can judge whether or not to connect to the AP2without performing transmission in A-BFT.

The AP2 may periodically include an EDMG TX RX Info element (see FIG. 5) in the DMG Beacon frame. Accordingly, the value of the EDMG TX RX Infofield at the AP2 can be notified to the AP1 without increasing the dataamount of the DMG Beacon frame.

FIG. 24 illustrates a different example of a DMG Beacon frame. UnlikeFIG. 23 , the EDMG TX RX Info field in FIG. 24 includes the DifferentialGain field (the same as in FIG. 18 ), Relative Beamed TX EIRP field, andRelative Beamed RX gain field (the same as in FIG. 20 ). The AP1 canshorten the fame length of the DMG Beacon as compared to that in FIG. 23by using the format for the DMG Beacon frame in FIG. 24 .

FIG. 25 illustrates an example of the procedures of the AP1 including anEDMG TX RX Info field relating to AP2 in a Neighbor Report Responseframe and transmitting.

In step S301A, the STA1 transmits a Neighbor Report Request frame to theAP1.

In step S301B, the AP1 transmits a Neighbor Report Response frame to theSTA1. FIG. 26 illustrates an example of a Neighbor Report Responseframe. The configuration of the EDMG TX RX Info field in FIG. 26 is thesame as in FIG. 25 .

The AP1 may include the Neighbor Report element including the EDMG TX RXInfo field in the Association Response frame, Authentication frame, DMGBeacon frame, Neighbor Report Response frame, BSS Transition ManagementQuery frame, BSS Transition Management Request, and BSS TransitionManagement Response frame.

Note that the AP1 may make notification of information relating to theNeighbor Report element including the EDMG TX RX Info field using acommunication format other than millimeter wave communication (11ad and11ay).

The communication device (AP) 100 a according to the third embodimenttransmits the TX EIRP field, A-BFT RX Antenna Gain field, Beamed TX EIRPfield, and Beamed RX gain field, relating to another AP, in the NeighborReport element in the DMG Beacon frame, so the communication device(STA) 100 b can judge whether desired throughput can be realized beforeassociation, and can connect with a suitable AP.

The communication device (AP) 100 a according to the third embodimentperiodically transmits the TX EIRP field, A-BFT RX Antenna Gain field,Beamed TX EIRP field, and Beamed RX gain field, relating to another AP,in the Neighbor Report element in the DMG Beacon frame, so the timerequired to transmit the DMG Beacon frame can be shortened.

The communication device (AP) 100 a according to the third embodimenttransmits the Differential Gain field, Relative Beamed TX EIRP field,and Relative Beamed RX gain field, relating to another AP, in theNeighbor Report element in the DMG Beacon frame, so the communicationdevice (STA) 100 b can judge whether desired throughput can be realizedbefore association, and can connect with a suitable AP.

Fourth Embodiment

In the first through third embodiments, the communication device (STA)100 b determines whether or not to transmit an SSW frame based on a DMGBeacon, and cancels connection with the communication device (AP) 100 ain a case of determining not to transfer. In a fourth embodiment, amethod will be described to transmit information necessary to establisha wireless link using another wireless format, even if judgment is madebased on the DMG Beacon not to transmit an SSW frame.

FIG. 27 is a diagram illustrating an example of procedures ofcommunication between the communication device (AP) 100 a (hereinafter,AP1) and communication device (STA) 100 b (hereinafter, STA1). In FIG.27 , the AP1 and STA1 include wireless units corresponding to acommunication format that differs from millimeter wave communication(hereinafter referred to as WLAN) besides millimeter wave communication(11ad and 11ay).

Examples of WLAN include the IEEE 802.11n format that uses the 2.4 GHzband and 5 GHz band. Another example of WLAN is the Bluetooth (aregistered trademark) format that uses the 2.4 GHz band. Cellularcommunication (e.g., Long Term Evolution (LTE)) may be used tosubstitute for WLAN. Multihop communication (also referred to as Relay)in millimeter wave communication (IEEE 802.11ad and IEEE 802.11ay) maybe used, as another example of WLAN. That is to say, in a case ofincluding information relating to a best sector in a Feedback frame andtransmitting the communication device (STA) 100 b may use Multihopcommunication instead of using WLAN.

In FIG. 27 , the AP1 and STA1 are in a state capable of datacommunication using WLAN. That is to say, in a case where the WLAN isthe IEEE 802.11ac format, the AP1 and STA1 are in a state where the STA1is associated with the AP1, and in a case where the WLAN is LTE, the AP1and STA1 are in a state where the STA1 is attached to the AP1.

Also, FIG. 27 illustrates a state where it is difficult for the AP1 toreceive an SSW frame that the STA1 transmits in a case of receivingpackets using the receiving q-omni antenna 115. That is to say, the AP1and STA1 are in a state corresponding to the state illustrated in FIG.3B, so communication by sector sweep is difficult. On the other hand,the AP1 and STA1 correspond to the states in FIGS. 3A, 3C, and 3D, andaccordingly are capable of data communication in a case where the bestsector can be set.

In a case where the gain of the transmitting array antenna 106 andreceiving array antenna 116 of the AP1 is greater as compared to thegain of the transmitting array antenna 106 and receiving array antenna116 of the STA1, the situation illustrated in FIG. 27 occurs. Forexample, a case where AP1 is a wireless bases station or access pointhaving a great number of antenna elements, and the STA1 is a mobileterminal (e.g., cellular phone or smartphone) having a relatively smallnumber of antenna elements, falls under this.

The AP1 also has Antenna Reciprocity. That is to say, thedirectionalities of the transmitting array antenna 106 and the receivingarray antenna 116 are generally equal. Accordingly, the probability thatthe best sector for the transmitting array antenna 106 is also the bestsector for the receiving array antenna 116 is high. The best sector atthe transmitting array antenna 106 is equal to or greater than asemi-best sector (i.e., a sector having a gain close to that of the caseof the best sector) at the receiving array antenna 116, and the bestsector at the receiving array antenna 116 is equal to or greater than asemi-best sector at the transmitting array antenna 106.

In step S401, the AP1 transmits the DMG Beacon frames in each sectorwhile changing sectors. The AP1 may include the TX EIRP field and A-BFTRX Antenna Gain field in the DMG Beacon frame and transmit (see FIGS. 5and 14 ). The AP1 may also include the Differential Gain field in theDMG Beacon frame and transmit (see FIG. 18 ). The AP1 also includesinformation of Antenna Reciprocity in the DMG Beacon, thereby notifyingthe STA1 that the AP1 has antenna reciprocity.

In step S401, the STA1 is in the positional relation illustrated in FIG.3A as to the AP1, and is capable of receiving a DMG Beacon.

The STA1 uses the reception power (RSSI_Beacon) of the DMG Beacon frameand information included in the DMG Beacon frame (e.g., the TX EIRPfield and A-BFT RX Antenna Gain field) to determine whether or not anSSW frame can reach the AP1 in A-BFT. In a case where determination ismade that it will be difficult for an SSW frame in A-BFT to reach theAP1, the STA1 does not transmit the SSW frame.

Note that an arrangement may be made where determination is maderegarding whether or not an SSW frame can reach the AP1, by the STA1transmitting the SSW frame in A-BFT and depending on whether or not anSSW-FB frame is received from the AP1 (step S402).

In A-BFT, the AP1 may receive an SSW frame from other STA besides theSTA1. That is to say, in A-BFT, the AP1 receives packets using thereceiving q-omni antenna 115. That is to say, the AP1 and STA1 are in arelation corresponding to the relation illustrated in FIG. 3B, so it isdifficult for an SSW frame transmitted by the STA1 in A-BFT to reach theAP1.

In a case of having judged that it will be difficult for an SSW frame inA-BFT to reach the AP1, the STA1 uses WLAN to transmit a Feedback frameto the AP1. The STA1 includes information of the best sector selected inreception of the DMG Beacon in the Feedback frame and transmits (stepS403).

FIG. 28 illustrates an example of Feedback frame. The Header field is aheader used in WLAN. For example, the Header field includes transmissiondestination address (MAC address of AP1), transmission source address(MAC address of the STA1), frame length, and so forth.

The DMG Source Address field includes the transmission source address(MAC address of the STA1) as an 11ad device. The DMG Destination Addressfield includes the transmission destination address (MAC address of AP1)as an 11ad device. That is to say, the MAC address for WLAN included inthe Header field and the MAC address for 11ad may be different for theAP1 and STA1.

The DMG Capabilities field includes information relating to attributesregarding the 11ad standard for the STA1. For example, the DMGCapabilities field includes the number of sectors that the STA1supports, MCS (Modulation Coding Scheme) No. supported, and so forth.These include information necessary for the AP1 to transmit/receive SSWframes in steps S405 and S406, described later. The AP1 may use the sameformat as the DMG Capabilities element stipulated in the 11ad standard,as the DMG Capabilities field in FIG. 28 .

The DMG SSW Feedback field includes best sector information selected bythe STA1 in DMG Beacon reception. The STA1 may use the same format asthe SSW Feedback field included in the SSW frame in A-BFT, as the DMGSSW Feedback field.

The AP1 transmits an Ack frame to the STA1 using WLAN, and makesnotification regarding reception of the Feedback frame (step S404).

The AP1 can know the best sector of the transmitting array antenna 106to be used in a case of transmitting data to the STA1 (i.e., FIG. 3C),by receiving the Feedback frame in step S403. The AP1 has antennareciprocity, so the best sector of the receiving array antenna 116 to beused in a case of receiving data from the STA1 (i.e., FIG. 3D) is set tobe the same as the best sector of the transmitting array antenna 106.

In step S405, the AP1 transmits an SSW frame to the STA1 using theinformation included in the Feedback frame (i.e., performs ISS). Forexample, the AP1 sets the destination address of the SSW frame to theMAC address for 11ad of the STA1 that has been obtained by the Feedbackframe, and transmits. The AP1 also decides the number of SSW frames tobe transmitted in accordance with information of the sector count of theSTA1 included in the DMG Capabilities field of the Feedback frame.

Note that the AP1 may transmit each SSW frame in each sector whilechanging sectors in step S405 (e.g., normal SLS). Alternatively, the AP1may transmit a single SSW frame in step S405, using the best sectorincluded in the Feedback frame.

In step S406, the STA1 transmits each SSW frame in each sector whilechanging sectors (i.e., performs RSS). In step S406, the AP1 sets thereceiving array antenna 116 to the best sector included in the Feedbackframe. That is to say, the positional relation between the AP1 and STA1is the same as in FIG. 3D in step S406, so SSW frames transmitted by theSTA1 can reach the AP1.

In step S407, the AP1 transmits an SSW-FB frame, notifying the STA1 thatthe SSW frame has been received.

In step S408, the STA1 transmits an SSW-ACK frame, notifying the AP1that the SSW-FB frame has been received. Thus, the communication device(STA) 100 b includes information relating to the best sector in aFeedback frame and transmits using WLAN, so even in a case where SSWframes in A-BFT do not reach the communication device (AP) 100 a (FIG.3B), SLS can be performed.

In this arrangement, the communication device (AP) 100 a sets thereceiving array antenna 116 to the best sector and performs SLS based oninformation received in a Feedback frame using WLAN, so SLS can beperformed even in a case of not receiving an SSW frame in A-BFT (FIG.3B) from the communication device (STA) 100 b. That is to say, thecommunication device (AP) 100 a is capable of communication with adistant communication device (STA) 100 b.

Next, a method of the STA1 performing association with the AP1 regarding11ad will be described. The AP1 sets the receiving q-omni antenna 115 toenabled and stands by, so the positional relation between the AP1 andSTA1 is that in FIG. 3B, and it is difficult for the STA1 to transmit anAssociation Request frame.

Accordingly, after step S408, the AP1 sets the transmitting arrayantenna 106 to the best sector, and transmits a Grant frame to the STA1(step S409). Note that hereinafter, the AP1 sets the transmitting arrayantenna 106 to the best sector in a case of transmitting packets to theSTA1, unless stated otherwise in particular.

In step S410, the STA1 transmits a Grant Ack frame to the AP1, to notifyof reception of the Grant. The STA1 transmits a Probe Request frame inthe range of the time period information included in the Grant frame instep S409. The AP1 sets the receiving array antenna 116 to the bestsector in the range of the time period information included in the Grantframe in step S409 (step S411).

That is to say, the positional relation between the AP1 and STA1corresponds to that in FIGS. 3C and 3D, in the range of the time periodinformation included in the Grant frame in step S409, so transmittedpackets can reach the AP1.

In step S412 through step S414, the AP1 transmits a Probe Responseframe, the STA1 transmits an Association Request frame, and the AP1transmits an Association Response frame. Thus, the STA1 completesassociation with the AP1.

Thus, the communication device (STA) 100 b includes information relatingto the best sector in a Feedback frame and transmits using WLAN, andtransmits an Association Request frame after having received a Grantframe, so even in a case where SSW frames in A-BFT do not reach thecommunication device (AP) 100 a, association by millimeter wavecommunication can be performed.

The communication device (AP) 100 a receives the Feedback frame usingWLAN, transmits a Grant frame, and sets the receiving array antenna 116to the best sector based on information of the Feedback frame in theperiod indicated by the Grant frame, and performs SLS, so even in a casewhere an SSW frame is not received in A-BFT from the communicationdevice (STA) 100 b, association by millimeter wave communication can beperformed.

Next, a method of the STA1 and AP1 performing data communication usingmillimeter wave communication (11ad and 11ay) will be described. The AP1sets the receiving q-omni antenna 115 to enabled and stands by, so thepositional relation between the AP1 and STA1 is that in FIG. 3B, and itis difficult for the STA1 to transmit data frames using 11 ad and 11 ay.

FIG. 27 illustrates procedures of the AP1 transmitting an RTS frame tothe STA1, and performs data communication with the STA1 (step S450through step S454).

In step S450 in FIG. 27 , the AP1 sets the transmitting array antenna106 to the best sector, and transmits an RTS frame to the STA1. The STA1may receive the RTS frame using the receiving q-omni antenna 115 (seeFIG. 3A).

FIG. 29 illustrates the format of an RTS frame in 11ad. The FrameControl field includes Type information indicating that the frame isRTS. The Duration field includes information of time period inincrements of microseconds, and indicates the time of the AP1 performingcommunication (TX opportunity (TXOP)) after the RTS frame. The RA fieldmeans receiving address, and in step S450 in FIG. 27 , the AP1 sets theRA field to the MAC address of the STA1. The TA field means transmittingaddress, and in step S450 in FIG. 27 , the AP1 sets the TA field to theMAC address of the STA1. The FCS (Frame check sequence) field includeserror detection code.

In a case of having received the RTS frame in which the address of theSTA1 has been set in the RA field, the STA1 transmits a CTS frame to theAP1. The AP1 sets the receiving array antenna 116 to the best sector,and receives the CTS frame. The TXOP is enabled when the AP1 receivesthe CTS frame (step S451).

The AP1 that has acquired the TXOP may transmit a data frame to theSTA1. The AP1 includes an RDG (Reverse Direction Grant) field in thedata frame addressed to the STA1 and transmits, thereby granting theSTA1 permission to transmit data (step 452).

In a case of having received a data frame including an RDG (permissionfor the STA1 to transmit), the STA1 includes a BA (Block Ack, i.e., areception configuration) regarding the data frame received in step S452in the data frame, and transmits to the AP1 (step 453).

The AP1 transmits a BA regarding the data frame of step S453 to the STA1(step S454).

As described above, the AP1 transmits an RTS frame to the STA1 andacquires a TXOP, sets the transmitting array antenna 106 and receivingarray antenna 116 to the best sector during the TXOP period, andtransmits an RDG to the STA1. Accordingly, even if reception of atransmission packet from the STA1 by the receiving q-omni antenna 115 isdifficult, data frames from the STA1 can be received using the receivingarray antenna 116.

The AP1 may transmit a Grant frame to the STA1 in step S450, instead ofthe RTS frame, receive a Grant Ack frame in step S451 instated of theCTS frame, and enable data communication with the STA1. These proceduresare the same as step S409 through S414, so description will be omitted.

Note that in step S409 and step S450 (in a case of transmitting a Grantframe), the AP1 may transmit a Poll frame to the STA1 beforetransmitting the Grant frame. The STA1 that has received the Poll frametransmits an SPR (Service period request) frame to the AP1, notifyingwhether or not it has data to be transmitted to the AP1. That is to say,the STA1 performs a transmission time allocation request to the AP1using an SPR.

The AP1 sets the receiving array antenna 116 to the best sector, andreceives the SPR frame. In a case of the STA1 having judged that datatransmission to the AP1 is necessary, the AP1 may transmit a Grant framein step S409 and step S450 (in a case of transmitting a Grant frame), inaccordance with the content of the SPR frame.

The AP1 may also include an ESE (Extended Schedule Element) in the DMGBeacon frame, and schedule the period for performing communication withthe STA1 (e.g., Allocation-1 in FIG. 30 ) (step S471).

FIG. 30 illustrates the format of an ESE in the 11ad standard. The AP1sets the value of the Source AID field of the Allocation-1 to theAssociation ID (AID) of the STA1, and sets the value of the DestinationAid field to the AID of the AP1. Note that an AID is a value regardingwhich a different value is decided for each STA at the time ofassociation, and is used instead of an address.

The AP1 includes information indicating the start clock time ofAllocation-1 in the Allocation Start field. Also, the AP1 includesinformation indicating time relating to Allocation-1 in the AllocationBlock Duration field. That is to say, the AP1 sets the receiving arrayantenna 116 to the best sector for performing communication with theSTA1 for an amount of time starting at the clock time that theAllocation Start field indicates, for the duration of time indicated bythe Allocation Block duration field.

Note that the AP1 may set a value of 2 or greater to the Number ofBlocks field, and repeat the time indicated by the Allocation Blockduration field (referred to as time block) multiple times, to decide thetime of Allocation-1. The AP1 keeps an interval of time indicated by theAllocation Block Period field between two time blocks. In this case, theAP1 sets the receiving array antenna 116 to the best sector to performcommunication with the STA1 at each time block.

As described above, the communication device (STA) 100 b according tothe fourth embodiment includes information relating to the best sectorin a Feedback frame, and transmits using WLAN, so even in a case whereSSW frames in A-BFT do not reach the communication device (AP) 100 a,SLS, association, and data communication can be performed by millimeterwave communication.

The communication device (AP) 100 a sets the receiving array antenna 116to the best sector and performs SLS, based on information from havingreceived the Feedback frame using WLAN, so SLS and data communicationcan be performed by millimeter wave communication even in a case whereSSW frames by A-BFT are not received from the communication device (STA)100 b, and communication can be performed with a distant communicationdevice (STA) 100 b.

Modification of First and Second Embodiments

Note that in a case of having reception capabilities that are high ascompared to the reception sensitivity level (FIG. 12A) set forth in thestandard, the communication device (AP) 100 a may include the differencebetween the value of the standard and reception capabilities inRxGain_ABFT and RxGain_AP_Data and transmit.

For example, in a case of handling reception of MCSO packets at −81 dBm(which is to say that reception capabilities are 3 dB higher due tobeing able to handle reception of signals 3 dB lower than thesensitivity level −78 dBm stipulated in the standard), the communicationdevice (AP) 100 a may include a value where 3 dB has been added to thevalue of RxGain_ABFT in the A-BFT RX Antenna Gain field (FIG. 5 ) andtransmit.

Expressing the value of the reception sensitivity level set forth in thestandard (see FIG. 12A) as SENSE REF, and the reception sensitivity ofthe communication device (AP) 100 a as SENSE_AP, additional gainADD_GAIN_AP is calculated by Expression 11.

ADD_GAIN_AP=SENSE_REF−SENSE_AP   (11)

Whether or not the communication device (STA) 100 b satisfies Expression12 may be determined in step S104 of FIG. 10 .

RSSI_ABFT>SENSE_AP   (12)

Expression 12 may be modified into the following Expressions 13A throughC, using Expression 1, Expression 2, and Expression 11.

EIRP_ABFT−PathLoss_Beacon+RxGain_ABFT>SENSE_REF−ADD_GAIN_AP   (13A)

EIRP_ABFT−(EIRP_Beacon+RxGain_Beacon−RSSI_Beacon)+RxGain_AB_FT>SENSE_REF−ADD_GAIN_AP  (13B)

(EIRP_ABFT−RxGain_Beacon+RSSI_Beacon)−(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP)>SENSE_REF  (13C)

In step S104 in FIG. 10 , the values of EIRP_ABFT, RxGain_Beacon,RSSI_Beacon, and SENSE_REF are known to the communication device (STA)100 b. The communication device (STA) 100 b makes determination usingExpression 13C by receiving the value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) from the communication device (AP)100 a.

That is to say, the communication device (STA) 100 b determines whetheror not an SSW frame in A-BFT will reach the communication device (AP)100 a, including the value of ADD GAIN_AP, so in a case where thereception capabilities of the communication device (AP) 100 a are highas compared to the sensitivity level of the standard, there are moresituations where determination can be made that an SSW frame will reachthe communication device (AP) 100 a.

In step S101 in FIG. 10 , the communication device (AP) 100 a maytransmit a DMG Beacon frame including the values of EIRP Beacon,RxGain_ABFT, and ADD_GAIN_AP. A method of the communication device (AP)100 a transmitting the values of EIRP_Beacon and RxGain_ABFT has beendescribed in the first embodiment, and a field indicating the value ofADD_GAIN_AP may be included in the EDMG TX RX Info element of the DMGBeacon in the same way (see FIG. 5 ).

The communication device (AP) 100 a may transmit a DMG Beacon frameincluding the value of (EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) in stepS101 in FIG. 10 . A method of the communication device (AP) 100 aincluding the value of (EIRP_Beacon−RxGain_ABFT) in the DifferentialGain field (see FIG. 18 ) and transmitting has been described in amodification of the second embodiment, and the communication device (AP)100 a may include a field indicating the value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) in the Differential Gain field andtransmit.

The communication device (AP) 100 a may decide the value of theDifferential Gain by reading “difference between value of TX EIRP andvalue of A-BFT RX Antenna Gain” as “value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP)”, and include and transmit in theDMG Beacon frame in FIG. 18 .

FIG. 31 is a diagram illustrating a different example of the format of aDMG Beacon frame. In FIG. 31 , the Quasi-omni TX field is a fieldindicating whether or not the DMG Beacon frame has been transmitted bythe transmitting q-omni antenna 105. Also, in FIG. 31 , the DifferentialGain field is four bits.

FIG. 32 is a diagram illustrating an example of the relation between thevalue of the Differential Gain field and the value of(EIRP_Beacon−RxGain_AB FT−ADD_GAIN_AP). In FIG. 32 , for every increasein the value of the Differential Gain field, the value of(EIRP_Beacon−RxGain_AB_FT−ADD_GAIN_AP) increases by 6 dB.

The communication device (AP) 100 a selects a value closest to the valueof (EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) from FIG. 32 and decides thevalue of the Differential Gain field, and transmits this. In a case ofnot notifying the value of (EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) to thecommunication device (STA) 100 b, the communication device (AP) 100 asets the value of the Differential Gain field to 15 (undefined), andincludes in a DMG Beacon frame and transmits.

As described above, the communication device (AP) 100 a includes theDifferential Gain field in a DMG Beacon frame and transmits, andaccordingly the communication device (STA) 100 b can determine whetheran SSW frame in A-BFT will reach the communication device (AP) 100 a ornot. Accordingly, transmission of unnecessary SSW frames can be avoided,so electric power consumption of the communication device (STA) 100 bcan be reduced, and unnecessary interference waves to other STAs can bereduced.

Also, the communication device (AP) 100 a calculates and transmits thevalue of the Differential Gain field based on the value of EIRP fortransmitting the DMG Beacon (EIRP Beacon), the reception antenna gain inA-BFT (RxGain ABFT), and the difference between the sensitivity level ofthe standard and reception capabilities (ADD_GAIN), so the communicationdevice (STA) 100 b can determine whether an SSW frame in A-BFT willreach the communication device (AP) 100 a or not. Accordingly,transmission of unnecessary SSW frames can be avoided, so electric powerconsumption of the communication device (STA) 100 b can be reduced, andunnecessary interference waves to other STAs can be reduced.

Fifth Embodiment

A method of the communication device (AP) 100 a and communication device(STA) 100 b performing communication, which is different from the firstthrough fourth embodiments, will be described in a fifth embodiment.

FIG. 33 is a diagram illustrating an example of the DMG Beacon framethat the communication device (AP) 100 a transmits. In contrast with theDMG Beacon frame in FIG. 31 including the Quasi-omni TX field andDifferential Gain field, the DMG Beacon frame in FIG. 33 includes an APSelection Parameter field.

FIG. 34 is a diagram illustrating an example of values of the APSelection Parameter field. In a case of transmitting the DMG Beaconframe using the transmitting q-omni antenna 105, the communicationdevice (AP) 100 a sets the value of the AP Selection Parameter field to0.

In a case of transmitting the DMG Beacon frame using the transmittingarray antenna (directional antenna) 106, the communication device (AP)100 a sets the value of the AP Selection Parameter field to a valueother than 0, in accordance with the value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP).

That is to say, the communication device (AP) 100 a selects a value (1through 14) that is closest to the value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) from FIG. 34 , decides the valueof the AP Selection Parameter field, and transmits. In a case of notnotifying the communication device (STA) 100 b of the value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP), the communication device (AP) 100a sets the value of the AP Selection Parameter field to 15 (undefined),and includes in the DMG Beacon frame and transmits.

Unlike the Differential Gain field in FIG. 31 , each time the value ofthe AP Selection Parameter field increases by 1, the value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) increases by 3 dB. That is to say,the communication device (AP) 100 a can accurately notify thecommunication device (STA) 100 b of the value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) by including the AP SelectionParameter field in the DMG Beacon frame and transmitting.

In a case of transmitting the DMG Beacon frame, the communication device(AP) 100 a notifies whether or not transmission is by the transmittingq-omni antenna 105 by whether or not the value of the AP SelectionParameter field is 0, instead of including the Quasi-omni TX field inFIG. 31 and transmitting, so the Quasi-omni TX field can be omitted.Thus, a greater number of Reserved bits in the DMG Beacon frame can besecured, e.g., two bits in FIG. 33 whereas this is one bit in FIG. 31 .

FIG. 35 is a flowchart illustrating reception processing of the DMGBeacon frame in FIG. 33 by the communication device (STA) 100 b. FIG. 35also illustrates processing of the communication device (STA) 100 bperforming an active scan, i.e., processing of the communication device(STA) 100 b transmitting a Probe Request frame to the communicationdevice (AP) 100 a and a Probe Response frame being received. Thecommunication device (STA) 100 b detects an access point to which thecommunication device (STA) 100 b can connect (e.g., the communicationdevice (AP) 100 a) by repeating the procedures of FIG. 35 for eachchannel.

In step S501, the communication device (STA) 100 b receives a DMG Beaconframe. The communication device (STA) 100 b measures the reception powerof the DMG Beacon frame (RSSI_Beacon).

In step S502, the communication device (STA) 100 b analyzes the receivedDMG Beacon frame, and extracts the value of the AP Selection Parameterfield. The communication device (STA) 100 b determines whether or notthe value of the extracted AP Selection Parameter field is 0, and if thevalue is 0, e.g., in a case of determining that the DMG Beacon frame hasbeen transmitted by the transmitting q-omni antenna 105, advances tostep S503. In a case where the value of the AP Selection Parameter fieldis 1, determination is made that the DMG Beacon frame has beentransmitted by a directional antenna, and the flow advances to stepS510.

In step S503, the communication device (STA) 100 b does not performbeamforming training in A-BFT, and accordingly performs the followingprocessing.

The communication device (STA) 100 b analyzes the received DMG Beaconframe, and determines whether or not A-BFT is scheduled. If A-BFT is notscheduled, the communication device (STA) 100 b advances to step S504.In a case where A-BFT is scheduled, the communication device (STA) 100 badvances to step S504 after the A-BFT period is completed.

Note that in a case where A-BFT is scheduled, in step S503 thecommunication device (STA) 100 b may advance to step S513 (thetransition from step S503 to step S513 is omitted from illustration).

In step S504, the communication device (STA) 100 b sets the transmissionRF circuit 104 (see FIG. 4 ) to transmit using the transmitting q-omniantenna 105, and transmits a Probe Request frame.

The communication device (STA) 100 b may transmit in step S504 using theformat for the Probe Request frame stipulated in the 11ad standard. Thecommunication device (STA) 100 b may also include a field in the ProbeRequest frame indicating transmission using the transmitting q-omniantenna 105, and transmit.

In step S505, the communication device (STA) 100 b receives a ProbeResponse frame transmitted by the communication device (AP) 100 a, andthe processing ends.

Next, a case where the AP Selection Parameter field is other than 0 willbe described in step S502.

In step S510, the communication device (STA) 100 b decides the value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) from the values of the received APSelection Parameter field, using FIG. 34 . The communication device(STA) 100 b calculates the estimated value (estimated reception power)of the reception power of the SSW frame at the communication device (AP)100 a from the calculated value of (EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP)and the RSSI_Beacon value measured in step S501. The estimated receptionpower may be calculated using the left side of Expression 13C.

In step S511, the communication device (STA) 100 b determines whether ornot the estimated reception power calculated in step S510 exceeds thesensitivity level power (SENSE REF). That is to say determination ofExpression 13C is performed.

In a case where the estimated reception power exceeds the sensitivitylevel power, the communication device (STA) 100 b advances to step S512.In a case where the estimated reception power does not exceed thesensitivity level power, the communication device (STA) 100 b advancestoe step S520.

In step S512, the communication device (STA) 100 b analyzes the receivedDMG Beacon frame, and determines whether or not A-BFT is scheduled. In acase where A-BFT is not scheduled, the flow returns to step S501, andthe next DMG Beacon frame is received. For example, the communicationdevice (STA) 100 b repeats step S501 through step S512 until the DMGBeacon frame regarding which A-BFT is scheduled has been received (thistransition is omitted from illustration).

In step S513, in a case where A-BFT has been scheduled for the receivedDMG Beacon frame (Yes in S512), the communication device (STA) 100 btransmits an SSW frame to the communication device (AP) 100 a, andperforms BF training. In a case of having received an SSW Feedback framethat the communication device (AP) 100 a transmits, the communicationdevice (STA) 100 b deems BF training to have been completed.

Also, in a case where no SSW Feedback frame is received at the time ofcompletion of the A-BFT period, in step S513 the communication device(STA) 100 b deems BF training to have been incomplete or BF training tohave failed. A cause for failed BF training is, for example, in a casewhere transmission of SSW frames by the communication device (STA) 100 band another STA overlap and SSW frame transmission signals compete, thecommunication device (AP) 100 a may not receive the SSW frame nortransmit the SSW Feedback frame.

In a case of having completed BF training in step S514, thecommunication device (STA) 100 b advances to step S515. In a case ofhaving not completed BF training, the communication device (STA) 100 badvances to step S516.

In step S515, the communication device (STA) 100 b transmits a ProbeRequest frame using the directional antenna set to the best sectordecided in the BF training in step S513, and advances to step S505.

In step S516, the communication device (STA) 100 b determines whether ornot the value of the AP Selection Parameter field in the DMG Beaconframe received in S501 is 0, and if the value is 0 advances to S504, butif the value is other than 0, advances to S501.

Note that a case where a determination of Yes is made in step S516 is acase where the communication device (STA) 100 b has transitioned fromstep S503 to S513 (this transition is omitted from illustration). Notethat the communication device (STA) 100 b may omit the determination instep S516, and transition to step S501 in the same way as in the case ofNo in step S516.

Next, the operations of the communication device (STA) 100 b in a casewhere the communication device (STA) 100 b has determined that theestimated reception power does not exceed the sensitivity level (No) instep S511 will be described.

In step S520, the communication device (STA) 100 b performs BF trainingnot using A-BFT. The communication device (STA) 100 b may perform the BFtraining method using Wi-Fi and DTI illustrated in steps S403 throughS408 illustrated in FIG. 27 , for example, as BF training not usingA-BFT. Alternatively, the communication device (STA) 100 b may performAsymmetric Beamforming Training illustrated in FIG. 36 (to be describedlater) as BF training not using A-BFT during the DTI period.

In step S520, in a case where a SSW Feedback frame or SSW-ACK frame (tobe described later) that the communication device (AP) 100 a transmitshas been received, the communication device (STA) 100 b deems BFtraining to have been completed.

Next, the DMG Beacon frame fields will be described with regard to“perform BF training that does not use A-BFT” of step S520 in FIG. 35 ,with reference to FIGS. 36 through 38 .

FIG. 36 is a diagram illustrating an example of a method of thecommunication device (AP) 100 a and communication device (STA) 100 bcarrying out BF training without using A-BFT, in step S520 in FIG. 35 .

First, the operations of the communication device (AP) 100 a will bedescribed. The communication device (AP) 100 a transmits DMG Beaconframes 5001 a, 5001 b, 5001 c, and 5001 d, with a TRN-N field attachedthereto, for each transmission sector in the BTI period.

FIG. 37 is a diagram illustrating an example of the format of a PHYpacket (referred to as a DMG Beacon packet) including frames of the DMGBeacon frames 5001 a, 5001 b, 5001 c, and 5001 d. The DMG Beacon packetis stipulated in the 11ad standard, in and includes the STF (ShortTraining Field), CEF (Channel Estimation Field), Header (header),Payload, AGC (Automatic Gain Control), and TRN (training) field.

The communication device (AP) 100 a includes multiple TRN-R subfields inthe TRN field attached to the DMG Beacon frames 5001 a, 5001 b, 5001 c,and 5001 d and transmits. The communication device (STA) 100 b performsreception, switching reception sectors for each TRN-R subfield of theTRN fields in the DMG Beacon frames 5001 a, 5001 b, 5001 c, and 5001 d.The communication device (STA) 100 b selects a reception sector of whichthe reception quality is good, and decides the best sector for thecommunication device (STA) 100 b.

In a case where the communication device (STA) 100 b has receptionantenna pattern reciprocity, the communication device (STA) 100 b setsthe best sector of the transmitting antenna and best sector of thereceiving antenna to be the same No. For example, in a case where thecommunication device (STA) 100 b has reception antenna patternreciprocity, and the communication device (STA) 100 b performs BFtraining of the receiving antenna, the best sector of the transmittingantenna may be decided in addition to the best sector of the receivingantenna.

The payload of the DMG Beacon packet in FIG. 37 includes the DMG Beaconframe. The DMG Beacon frame includes a Frame Control field, Durationfield, BSSID field, Frame Body field, and FCS field.

The DMG Beacon frames 5001 a, 5001 b, 5001 c, and 5001 d include aTimestamp field, SSW (Sector Sweep) field, Extended Schedule element(referred to as ESE), and EDMG(Enhanced Directional Multi-Gigabit)Extended Schedule element (referred to as EDMG ESE).

FIG. 38 is a diagram illustrating an example of the format of the SSWfield in the DMG Beacon frames 5001 a, 5001 b, 5001 c, and 5001 d. TheSSW field includes a Direction subfield, CDOWN subfield, Sector IDsubfield, DMG Antenna ID subfield, AP Selection Parameter subfield, andReserved subfield.

In the BTI, the communication device (AP) 100 a transmits a DMG Beaconframe where the value of the CDOWN subfield has been reduced by one eachDMG Beacon frame. For example, in a case where the value of the CDOWNsubfield in the DMG Beacon frame 5001 a is n (where n is an integer of 1or greater), the communication device (AP) 100 a sets the value of theCDOWN subfield in the DMG Beacon frame 5001 b to be transmitted nextafter the DMG Beacon frame 5001 a to be n−1. A value k of the CDOWNsubfield is an integer of 0 or greater.

Also, the communication device (AP) 100 a includes the value of thetransmitting antenna No. (sector ID) to be used for transmitting the DMGBeacon frame in the Sector ID subfield of the DMG Beacon frame andtransmits. For example, the sector ID of the DMG Beacon frame 5001 a isS(n) (where S(n) is an integer that is 1 or greater but 64 or smaller),and the sector ID of the DMG Beacon frame 5001 b is S(n−1) (where S(n−1)is an integer that is 1 or greater but 64 or smaller).

The communication device (AP) 100 a decides the value of the APSelection Parameter subfield in the DMG Beacon frame 5001 a based on thetransmission EIRP where the sector ID is S(n), the gain of the receivingq-omni antenna, and the value of the additional gain (see FIG. 34 ).

An example of the format of the ESE in the DMG Beacon frames 5001 a,5001 b, 5001 c, and 5001 d has been illustrated in FIG. 30 , forexample. In FIG. 36 , the communication device (AP) 100 a schedules anAsymmetric BT allocation period in the DTI period. For example, thevalue of an Allocation Start subfield of one allocation field (e.g.,allocation-p, where p is an integer of 1 or greater) in the ESE, is setto the start clock time of Asymmetric BT allocation, to allocate time.Also, the communication device (AP) 100 a sets the values of theAllocation Block Duration subfield of allocation-p, Number of Blockssubfield, and Allocation Block Period subfield, to represent the periodof Asymmetric BT allocation.

Here, the communication device (AP) 100 a sets the value of the SourceAID of Allocation-p to 255 (a value indicating broadcast), and notifiesthat any communication device may start transmission in the AsymmetricBT allocation period indicated by Allocation-p. The communication device(AP) 100 a may also set the value of Destination AID to the AssociationID of the communication device (AP) 100 a (e.g., 0).

FIG. 39 is a diagram illustrating an example of the format of the EDMGESE of the DMG Beacon frames 5001 a, 5001 b, 5001 c, and 5001 d. TheEDMG ESE includes an Element ID field, Length field, Element IDExtension field, Number of Allocations field, and an M count of ChannelAllocation fields (where M is an integer of 1 or greater, and q is aninteger of 1 or greater but smaller than M).

The Channel Allocation field includes a Scheduling Type subfield,Allocation Key subfield, Channel Aggregation subfield, BW (Bandwidth)subfield, Asymmetric Beamforming Training subfield, Receive Directionsubfield, and Reserved subfield.

In a case of scheduling Asymmetric BT allocation in the DTI, thecommunication device (AP) 100 a sets the value of the AsymmetricBeamforming Training subfield in one Channel allocation field (e.g.,Channel allocation-q) to 1.

The communication device (AP) 100 a also includes the value of part(e.g., Allocation AID subfield, omitted from illustration) of theAllocation Control subfield (see FIG. 30 ) of the allocation-p of theESE in the Allocation Key subfield of Channel allocation-q.

By setting the value of the Asymmetric Beamforming Training subfield to1, the communication device (AP) 100 a makes notification thatAsymmetric BT allocation is present in the DTI, and by including thevalue of the AID of Allocation of the allocation-p of the ESE in theAllocation Key subfield in the Cannel allocation-q, makes notificationthat the start clock time and duration of the Asymmetric BT allocationis the same as the start clock time and duration of the allocation-p.

The communication device (AP) 100 a also sets the value of the ReceiveDirection subfield to the value of CDOWN of the DMG Beacon transmittedfirst in the BTI (e.g., n, which is the value of CDOWN of the DMG Beacon5001 a in FIG. 36 ). This value is referred to as CDOWN initial value.

Now, the processing at the communication device (AP) 100 a andcommunication device (STA) 100 b in the BTI in FIG. 36 corresponds tostep S501 in FIG. 35 . First, the communication device (AP) 100 atransmits the DMG Beacon packet in FIG. 37 , and schedules Asymmetric BTallocation. Also, when receiving the DMG Beacon packet, thecommunication device (STA) 100 b measures the reception power of the DMGBeacon packet, and performs receiving antenna training using the TRN-Rsubfield. Further, the communication device (STA) 100 b decides the bestsector for the transmitting antenna from antenna pattern reciprocity.

Next, in a case of having made determination of No in both steps S502and S511 in FIG. 35 , the communication device (STA) 100 b omitstransmission of an SSW frame in A-BFT in FIG. 36 .

Next, at the start clock time of Asymmetric BT allocation in FIG. 36 ,the communication device (AP) 100 a sets the receiving antenna to thesame sector as the DMG Beacon transmitted first (e.g., DMG Beacon 5001a) in the BTI (e.g., sector with Sector ID of S(n), referred to as firstsector).

After a predetermined amount of time (e.g., slot time) has elapsed fromthe start clock time of Asymmetric BT allocation, the communicationdevice (AP) 100 a switches the receiving antenna to the same sector asthe DMG Beacon transmitted second (e.g., DMG Beacon 5001 b) in the BTI(e.g., sector with Sector ID of S(n−1), referred to as second sector).

Note that the duration that the communication device (AP) 100 a sets tothe first sector is slot 1 (slot #1) and the duration set to the secondsector is slot 2 (slot #2).

Thus, from the start clock time of Asymmetric BT allocation, thecommunication device (AP) 100 a sequentially switches reception sectorseach slot time, and stands by. The communication device (AP) 100 aperforms switching of reception sectors in Asymmetric BT allocation inthe same order as performing switching of transmission sectors in DMGBeacon transmission.

Next, operations of the communication device (STA) 100 b will bedescribed. In the BTI, the communication device (STA) 100 b measures thereception quality for each reception of a DMG Beacon frame, and decidesthe sector ID of a DMG Beacon frame with good quality to be the bestsector for the communication device (AP) 100 a.

For example, the communication device (STA) 100 b decides the bestsector of the communication device (AP) 100 a (e.g., sector ID ofS(n−2)) by receiving the payload of a DMG Beacon packet using thereceiving q-omni antenna 115 in the BTI, switches the receiving arrayantenna (directional antenna) 116, and receives a TRN-R field, therebydeciding the best sector for the communication device (STA) 100 b.

The communication device (STA) 100 b sets the transmission sector to thebest sector of the communication device (STA) 100 b in Asymmetric BTallocation, and transmits SSW frame 5001 d.

In order for the SSW frame 5001 d to reach the communication device (AP)100 a, the communication device (STA) 100 b transmits the SSW frame tothe communication device (AP) 100 a in the positional relation in FIG.3D. Accordingly, the communication device (STA) 100 b transmits the SSWframe in a slot where the reception sector has been set to S(n-2) by thecommunication device (AP) 100 a.

Note that the communication device (AP) 100 a decides which slot is theslot for the communication device (AP) 100 a to set the reception sectorto S(n−2) as follows. In the BTI, it is difficult for the communicationdevice (STA) 100 b to distinguish what number DMG Beacon frame insequence the received DMG Beacon frame is from the reception clock time.The reason is that the length (occupation time) of the DMG Beacon frameis variable. Also, the DMG Beacon frame is transmitted from thetransmitting array antenna (directional antenna) 106, so there are caseswhere the communication device (STA) 100 b does not receive all DMGBeacon frames.

For example, in a case of the communication device (STA) 100 b receivinga DMG Beacon frame 300 microseconds after the start clock time of theBTI, it is difficult for the communication device (STA) 100 b todistinguish what number DMG Beacon frame in sequence the received DMGBeacon frame is (i.e., how many DMG Beacons have been transmitted in theaforementioned 300 microseconds), based on the time (300 microseconds).

Now, the communication device (STA) 100 b is able to distinguish whatnumber DMG Beacon frame in sequence the received DMG Beacon frame is,from the difference between the CDOWN initial value included in theReceive Direction subfield of the received DMG Beacon and the value ofthe CDOWN subfield in the SSW field of the received DMG Beacon.

For example, in FIG. 36 , the value of the Receive Direction subfield inFIG. 39 is n, and the value of the CDOWN subfield of the DMG Beaconframe corresponding to the best sector (e.g., DMG Beacon frame 5001 c)is n−2, so the communication device (STA) 100 b adds 1 to the difference(n−(n−2)=2) of the respective values, and distinguishes that the DMGBeacon frame 5001 c is the DMG Beacon frame transmitted third.

Accordingly, the communication device (STA) 100 b transmits the SSWframe 5001 d in slot 3 in the DTI. The communication device (AP) 100 asets the reception sector to the same sector in which the DMG Beaconframe 5001 c was transmitted in slot 3, and stands by for the SSW frame.Accordingly, the communication device (STA) 100 b can transmit an SSWframe to the communication device (AP) 100 a that is in the positionalrelation in FIG. 3D, and the communication device (AP) 100 a can receivethe SSW frame.

Now, in a case of having received an SSW frame that the communicationdevice (STA) 100 b has transmitted, the communication device (AP) 100 adeems the BF training to have succeeded. The communication device (AP)100 a may transmit an SSW-ACK (Sector Sweep Acknowledgement) frame tothe communication device (STA) 100 b, to notify that BF training hassucceeded.

So far, description has been made regarding the “perform BF trainingthat does not use A-BFT” in step S520 in FIG. 35 .

In step S521 in FIG. 35 , in a case where BF training has been completed(Yes), the communication device (STA) 100 b advances to step S522. In acase where BF training has not been completed (No), the communicationdevice (STA) 100 b advances to step S516.

In step S522, the communication device (STA) 100 b obtains a directionalTXOP in order to transmit a Probe Request frame to the communicationdevice (AP) 100 a. In order to acquire a directional TXOP, thecommunication device (STA) 100 b may standby until the communicationdevice (AP) 100 a transmits a frame including an ESE where the source(originator) address is the communication device (STA) 100 b, and thedestination (addressee) address is the communication device (AP) 100 a(e.g., DMG Beacon, see step S471 in FIG. 27 ).

The communication device (AP) 100 a sets the receiving array antenna tothe best sector for communicating with the communication device (STA)100 b in the period (allocation) specified by the above-described ESE.

Note that the communication device (AP) 100 a may include the Sector IDof the best sector in the Receive Direction field of the EDMG ESE, andset the receiving array antenna to the best sector for communicatingwith the communication device (STA) 100 b in the period specified by theEDMG ESE (this period is referred to as allocation of directionality).

For example, in a case where the communication device (AP) 100 aspecifies that one allocation of EDMG ESE (e.g., allocation-p) isAsymmetric BF allocation, the Asymmetric Beamforming Training field ofallocation-p is set to 1, and the CDOWN initial value is included in theReceive Direction field. Also, in a case where the communication device(AP) 100 a specifies that another one allocation of EDMG ESE (e.g.,allocation-q) is a directional allocation, the Asymmetric BeamformingTraining field of allocation-q is set to 0, and the Sector ID of thebest sector is included in the Receive Direction field.

Note that in a case of having received an SSW frame from thecommunication device (STA) 100 b before association in Asymmetric BFallocation, the communication device (AP) 100 a may use a DMG Beaconframe in the BTI after the Asymmetric BF allocation to allocate one ormore directional allocations, or may allocate one or more directionalallocations to multiple beacon intervals.

The communication device (AP) 100 a may decide the allocation method fordirectional allocation, in accordance with whether the communicationdevice (STA) 100 b is before or after association. In a case where thecommunication device (STA) 100 b is before association, for example, thecommunication device (STA) 100 b transmits a Probe Request frame,Association Request frame, and Authentication Request, but theproportion that the amount of data of frames related to this controloccupies in the amount of data that can be transmitted in a singlebeacon interval is small, so the communication device (AP) 100 a maytransmit an ESE or grant frame, and allocate directional allocation to asingle beacon interval.

Also, in a case where the communication device (STA) 100 b is afterassociation, for example, the communication device (STA) 100 b transmitsa data frame, but amount of data that a data frame occupies in theamount of data that can be transmitted in a single beacon interval isgreat, so the communication device (AP) 100 a may transmit an ESE orgrant frame, and allocate directional allocation to a multiple beaconintervals. Note that directional allocation may be allocated to multiplebeacon intervals even of the communication device (STA) 100 b is beforeassociation.

The communication device (STA) 100 b may transmit an SSW frame inAsymmetric BF allocation even after association, and the communicationdevice (AP) 100 a may request scheduling of directional allocation.Accordingly, the communication device (AP) 100 a periodically schedulesdirectional allocation, so usage efficiency of wireless resources isimproved, and throughput can be improved.

Also, in step S522, the communication device (STA) 100 b may standby fortransmission of a Grant frame from the communication device (AP) 100 a(see step S409 in FIG. 27 ) and transmission of an RTS frame from thecommunication device (AP) 100 a (see step S450 in FIG. 27 ).

The communication device (AP) 100 a sets the receiving array antenna 116to the best sector for communicating with the communication device (STA)100 b over the period (allocation) that the aforementioned Grant framespecifies. The communication device (AP) 100 a also sets the receivingarray antenna 116 to the best sector for communicating with thecommunication device (STA) 100 b over the period that the aforementionedRTS frame specifies.

In step S523, the communication device (STA) 100 b uses the transmittingarray antenna (directional antenna) 106 set to the best sector decidedin the BF training in step S520 to transmit a Probe Request frame. Thecommunication device (AP) 100 a has set the receiving array antenna 116to the best sector for communicating with the communication device (STA)100 b, so even in a case where determination of No has been made in stepS511 (e.g., an SSW frame in A-BFT will not reach the communicationdevice (AP) 100 a from the communication device (STA) 100 b), the ProbeRequest frame that the communication device (STA) 100 b has transmittedwill reach the communication device (AP) 100 a.

After having transmitted a Probe Request frame, the communication device(STA) 100 b advances to step S505. Note that in a case where the DMGBeacon packet received in step S501 includes a TRN-R subfield, and alsothe value of the AP Selection Parameter field is 0, the communicationdevice (STA) 100 b may perform training for the best sector for thecommunication device (STA) 100 b using the TRN-R subfield, and transmita Probe Request using the best sector (transmitting array antenna 106)of the communication device (STA) 100 b instead of using thetransmitting q-omni antenna 105 in step S504.

Note that in a case where the DMG Beacon packet received in step S501includes a TRN-R subfield, and also a determination of No has been madein step S502 and step S511, the communication device (STA) 100 b mayadvance to step S523 instead of performing Asymmetric BT in step S520,and use Wi-Fi instead of using the transmitting array antenna(directional antenna) 106 to transmit a Probe Request frame to thecommunication device (AP) 100 a.

The communication device (STA) 100 b may also transmit a Probe Requestframe using OCT (On-channel Tunneling). The communication device (STA)100 b may transmit a Probe Request frame format according to the 11adand 11ay standards using Wi-Fi.

Note that the communication device (STA) 100 b may include an SSWFeedback field in the Probe Request frame and transmit. Accordingly, thecommunication device (STA) 100 b can notify the communication device(AP) 100 a of the best sector without performing BF training using A-BFT(step S513) or BF training not using A-BFT (step S520), so delayrequired for BF training can be reduced, and inference on other STAs dueto BF training can be reduced.

The steps of FIG. 35 have been described so far. Note that in a casewhere a predetermined amount of time elapses after starting theoperations of FIG. 35 , the communication device (STA) 100 b ends theoperations of FIG. 35 even if step S505 has not been performed.

According to the above, in step S502 in FIG. 35 , the communicationdevice (STA) 100 b determines whether or not the value of the APSelection Parameter field is 0, and in a case where the value is 0,transmits a Probe Request frame using the transmitting q-omni antenna105, so a Probe Response frame can be received, omitting execution ofthe BF training in step S513 and step S520. Accordingly, thecommunication device (STA) 100 b can reduce the amount of time necessaryfor an active scan, and initial connection operations with thecommunication device (AP) 100 a can be completed at an early stage anddata communication can be started.

Also, in step S512 in FIG. 35 , the communication device (STA) 100 b canuse the value of the AP Selection Parameter field to determine whetheror not an SSW frame in A-BFT will reach the communication device (AP)100 a. In a case of having determined that an SSW frame will reach thecommunication device (AP) 100 a, the communication device (STA) 100 bperforms BF training using A-BFT (step S513). BF training using A-BFThas a shorter delay as compared with BF training not using A-BFT, so thecommunication device (STA) 100 b can complete BF training at an earlystage, and can complete active scanning at an early stage.

Also, in step S511 of FIG. 35 , in a case of determining that an SSWframe will not reach the communication device (AP) 100 a, thecommunication device (STA) 100 b performs BF training not using A-BFT(step S520), thereby suppressing transmission of SSW frames in A-BFT,which can reduce interference as to the communication device (AP) 100 a,other APs, and other STAs.

Also, the communication device (AP) 100 a includes the AP SelectionParameter field in the DMG Beacon and transmits, so the STA that hasreceived the DMG Beacon (e.g., the communication device (STA) 100 b) cancomplete active scanning at an early stage, and start data communicationwith the communication device (AP) 100 a.

As described above, the communication device (AP) 100 a transmits theDMG Beacon frame with the AP Selection Parameter field included, sowhether or not the Probe Request frame will reach the communicationdevice (AP) 100 a by Quasi-omni transmission can be determined at thecommunication device (STA) 100 b. Accordingly, the communication device(AP) 100 a can avoid transmission of unnecessary SSW frames in A-BFT, sothe electric power consumption of the communication device (STA) 100 bcan be reduced, and occurrence of unnecessary interference waves as toother STAs can be reduced.

Also, the communication device (AP) 100 a transmits the DMG Beacon frameincluding the EDMG ESE field scheduling Asymmetric BT allocation, and afield indicating the CDOWN initial value (Receive Direction field), sothe communication device (STA) 100 b can distinguish the order of theDMG Beacon frame corresponding to the best sector, and can decide a timeslot where an SSW frame can reach the communication device (AP) 100 a inAsymmetric BT allocation.

Accordingly, even in cases where the transmission power of thecommunication device (AP) 100 a and communication device (STA) 100 b aredifferent, the communication device (STA) 100 b can complete beamformingtraining. Thus, the communication device (AP) 100 a can have a widecoverage area.

Sixth Embodiment

Another method for the communication device (AP) 100 a and communicationdevice (STA) 100 b to communicate will be described in a sixthembodiment. FIG. 40 is a diagram illustrating an example of a DMG Beaconframe transmitted by the communication device (AP) 100 a. In comparisonwith the DMG Beacon frame in FIG. 31 that includes the Quasi-omni TXfield and Differential Gain field, the DMG Beacon frame in FIG. 40includes the Differential Gain field and does not include the Quasi-omniTX field.

The communication device (AP) 100 a sets the value of the DifferentialGain field to one of values (0 through 14) corresponding to the value of(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) and a value (15) corresponding toundefined, in the same way as the modification of the first and secondembodiments (FIG. 32 ), and transmits the DMG Beacon frame with theDifferential Gain field included.

FIG. 41 is a flowchart illustrating reception processing of the DMGBeacon frame in FIG. 40 by the communication device (STA) 100 b. Notethat the communication device (STA) 100 b may perform the receptionprocessing in FIG. 41 in a case of having received the DMG Beacon framein FIG. 31 . Steps that are the same processing as in FIG. 35 aredenoted by the same symbols, and description will be omitted.

In step S601, the communication device (STA) 100 b receives the DMGBeacon frame. The communication device (STA) 100 b measures thereception power of the DMG Beacon frame (RSSI_Beacon).

In step S602, the communication device (STA) 100 b decides the value of(EIRP_Beacon−RxGain ABFT−ADD_GAIN_AP) from the value of the DifferentialGain field included in the received DMG Beacon frame, using FIG. 32 .

The communication device (STA) 100 b calculates an estimation value ofreception power of an SSW frame by the communication device (AP) 100 ain a case where the communication device (STA) 100 b has transmittedusing the transmitting q-omni antenna 105 (referred to as “estimatedreceived power in Quasi-omni transmission”), based on the calculatedvalue of (EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) and the RSSI_Beacon valuemeasured in step S601.

The communication device (STA) 100 b also calculates an estimation valueof reception power of an SSW frame by the communication device (AP) 100a in a case where the communication device (STA) 100 b has transmittedusing the transmitting array antenna (directional antenna) 106 (referredto as “estimated received power in directional transmission”), based onthe calculated value of (EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP) and theRSSI_Beacon value measured in step S601.

In step S603, the communication device (STA) 100 b determines whether ornot the estimated received power in Quasi-omni transmission calculatedin step S602 exceeds the sensitivity level power (SENSE_REF). That is tosay, determination of the following Expression 14 is performed.

(EIRP_ABFT_Qomni−RxGain_Beacon+RSSI_Beacon)−(EIRP_Beacon−RxGain_ABFT−ADD_GAIN_AP)>SENSE_REF   (14)

Note that the communication device (STA) 100 b may calculate theestimated received power in Quasi-omni transmission using the left sideof Expression 14 in step S602.

In a case where the estimated received power in Quasi-omni transmissionexceeds the sensitivity level power (Yes in S603), the communicationdevice (STA) 100 b advances to step S604.

In a case where the estimated received power in Quasi-omni transmissiondoes not exceed the sensitivity level power (No in S603), thecommunication device (STA) 100 b advances to step S610.

In step S604, the communication device (STA) 100 b performs thefollowing processing to not perform beamforming training in A-BFT. Thecommunication device (STA) 100 b analyzes the received DMG Beacon frame,and determines whether or not A-BFT is scheduled. In a case where A-BFTis not scheduled, the communication device (STA) 100 b advances to stepS605. In a case where A-BFT is scheduled, the communication device (STA)100 b advances to step S605 after the A-BFT period has been completed.

Note that in a case where A-BFT is scheduled in step S604, thecommunication device (STA) 100 b may advance to step S513 (thetransition from step S604 to step S513 is omitted from illustration).

In step S605, the communication device (STA) 100 b sets the transmissionRF circuit 104 (see FIG. 4 ) to transmit using the transmitting q-omniantenna 105, and transmits a Probe Request frame.

In step S605, the communication device (STA) 100 b may transmit usingthe format of the Probe Request frame stipulated in the 11ad standard.The communication device (STA) 100 b may also include a field indicatingthat transmission will be performed using the transmitting q-omniantenna 105 in the Probe Request frame, and transmit.

In step S606, the communication device (STA) 100 b receives a ProbeResponse frame transmitted by the communication device (AP) 100 a, andthe processing ends.

Next, a case where the communication device (STA) 100 b has determinedin step S603 that the estimated received power in Quasi-omnitransmission does not exceed the sensitivity level power will bedescribed.

In step S610, the communication device (STA) 100 b determines whether ornot the estimated received power in directional transmission calculatedin step S602 exceeds the sensitivity level power (SENSE_REF). That is tosay, the determination of Expression 13C is performed.

In a case where the estimated received power in directional transmissionexceeds the sensitivity level power (Yes in S610), the communicationdevice (STA) 100 b advances to step S513. In a case where the estimatedreceived power not exceed the sensitivity level power (No in S610), thecommunication device (STA) 100 b advances to step S520.

Also, in S614, the communication device (STA) 100 b determines whetheror not the estimated received power in Quasi-omni transmissioncalculated in step S602 exceeds the sensitivity level power (SENSE_REF),and if exceeding (Yes) advances to step S605, and if not exceeding (No)advances to step S601. The steps in FIG. 41 have thus been described.

Note that in a case where a predetermined amount of time has elapsedfrom starting the operations of FIG. 41 , the communication device (STA)100 b ends the operations of FIG. 41 even if step S606 has not beenexecuted.

As described above, in the reception processing in FIG. 35 , thecommunication device (STA) 100 b references the value of the APSelection Parameter field and judges whether or not to transmit a ProbeRequest using the transmitting q-omni antenna 105, but in the receptionprocessing in FIG. 41 , the communication device (STA) 100 b referencesthe value of the Differential Gain field and judges whether or not totransmit a Probe Request using the transmitting q-omni antenna 105.

Also, by performing the reception processing in FIG. 41 , in a case ofhaving transmitted a Probe Request frame using the transmitting q-omniantenna 105, the communication device (STA) 100 b can omit execution ofthe BF training in step S513 and S520, in the same way as using thereception processing in FIG. 35 , and receive a Probe Response frame.Accordingly, the communication device (STA) 100 b can reduce the timerequired for an active scan, and can complete initial connectionoperations with the communication device (AP) 100 a at an early stageand start data communication.

As described above, the communication device (AP) 100 a transmits a DMGBeacon frame including the Differential Gain field, so the communicationdevice (STA) 100 b can determine whether or not a Probe Request framewill reach the communication device (AP) 100 a by Quasi-omnitransmission. Accordingly, transmission of unnecessary SSW frames inA-BFT can be avoided, so electric power consumption of the communicationdevice (STA) 100 b can be reduced, and occurrence of unnecessaryinterference waves as to other STAs can be reduced.

Summarization of Embodiments

A non-personal basic service point/access point (PCP/AP) communicationdevice according to a first aspect of the present disclosure includes areception circuit that receives a DMG Beacon frame, a judging circuitthat judges whether or not to transmit a frame used for beamformingtraining (BFT), using information relating to reception antenna gain ofa PCP/AP communication device included in a DMG Beacon frame andinformation relating to reception power of a DMG Beacon frame, and atransmission circuit that transmits the frame used for BFT in a case ofthe judging circuit having judged to transmit the frame used for BFT.

A non-personal basic service point/access point (PCP/AP) communicationmethod according to a second aspect of the present disclosure includesreceiving a DMG Beacon frame, judging whether or not to transmit a frameused for beamforming training (BFT), using information relating toreception antenna gain of a PCP/AP communication device included in aDMG Beacon frame and information relating to reception power of a DMGBeacon frame, and transmitting the frame used for BFT in a case ofhaving judged to transmit the frame used for BFT.

A personal basic service point/access point (PCP/AP) communicationdevice according to a third aspect of the present disclosure includes aframe generating circuit that generates a DMG Beacon frame includinginformation relating to reception antenna gain of a PCP/AP communicationdevice, and a transmission circuit that transmits the DMG Beacon framein BTI.

A personal basic service point/access point (PCP/AP) communicationmethod according to a fourth aspect of the present disclosure includesgenerating a DMG Beacon frame including information relating toreception antenna gain of a PCP/AP communication device, andtransmitting the DMG Beacon frame in BTI.

Although various embodiments have been described above with reference tothe drawings, it is needless to say that the present disclosure is notrestricted to these examples. It is clear that one skilled in the artwill be able to reach various alterations and modifications within thescope of the Claims, and such should be understood to belong to thetechnical scope of the present disclosure as a matter of course. Variouscomponents in the above-described embodiments may be optionally combinedwithout departing from the essence of the disclosure.

Although examples of configuring the present disclosure using hardwarehave been described in the above-described embodiments, the presentdisclosure may be realized by software in cooperation with hardware aswell.

The functional blocks used in the description of the above-describedembodiments typically are realized as large-scale integration (LSI) thatis an integrated circuit having input terminals and output terminals.These may be individually formed into one chip, or part or all may beincluded in one chip. Also, while description has been made hereregarding an LSI, there are different names such as integrated circuit(IC), system LSI, super LSI, and ultra LSI, depending on the degree ofintegration.

The circuit integration technique is not restricted to LSIs, anddedicated circuits or general-purpose processors may be used to realizethe same. An FPGA (Field

Programmable Gate Array) which can be programmed after manufacturing theLSI, or a reconfigurable processor where circuit cell connections andsettings within the LSI can be reconfigured, may be used.

Further, in the event of the advent of an integrated circuit technologywhich would replace LSIs by advance of semiconductor technology or aseparate technology derived therefrom, such a technology may be used forintegration of the functional blocks, as a matter of course. Applicationof biotechnology, for example, is a possibility.

An aspect of the present disclosure is suitable for a communicationsystem conforming to the 11ay standard.

What is claimed is:
 1. A personal basic service set control point/accesspoint (PCP/AP) communication apparatus, comprising: a frame generatingcircuit which, in operation, generates a Directional Multi-Gigabit (DMG)Beacon frame including a sector sweep (SSW) field, the SSW fieldincluding a Parameter subfield indicating a value obtained by using atransmission Equivalent Isotropic Radiated Power (EIRP) of the PCP/APcommunication apparatus and a reception antenna gain of the PCP/APcommunication apparatus; a transmission circuit which, in operation,transmits the DMG Beacon frame in a Beacon Transmission Interval (BTI)to a non-PCP/AP communication partner apparatus; and a reception circuitwhich, in operation, receives a frame for Association BeamformingTraining (A-BFT) transmitted from the non-PCP/AP communication partnerapparatus based on the value of the Parameter subfield.
 2. The PCP/APcommunication apparatus according to claim 1, wherein an expectedreception power at the PCP/AP communication partner apparatus isestimated by using the value of the Parameter subfield, and inequalitybetween the estimated expected reception power and a receiversensitivity value is checked by the non-PCP/AP communication partnerapparatus.
 3. The PCP/AP communication apparatus according to claim 2,wherein if the estimated expected reception power is equal to or lessthan the receiver sensitivity value, the A-BFT is skipped.
 4. The PCP/APcommunication apparatus according to claim 1, wherein the value of theParameter subfield is obtained by subtracting the reception antenna gainfrom the transmission EIRP.
 5. The PCP/AP communication apparatusaccording to claim 4, wherein the value of the Parameter subfield isobtained by further subtracting an additional gain from the transmissionEIRP, the additional gain being a difference between a receiversensitivity value and an actual receiver sensitivity value.
 6. Acommunication method for a personal basic service set controlpoint/access point (PCP/AP) communication apparatus, the communicationmethod comprising: generating a Directional Multi-Gigabit (DMG) Beaconframe including a sector sweep (SSW) field, the SSW field including aParameter subfield indicating a value obtained by using a transmissionEquivalent Isotropic Radiated Power (EIRP) of the PCP/AP communicationapparatus and a reception antenna gain of the PCP/AP communicationapparatus; transmitting the DMG Beacon frame in a Beacon TransmissionInterval (BTI) to a non-PCP/AP communication partner apparatus; andreceiving a frame for Association Beamforming Training (A-BFT)transmitted from the non-PCP/AP communication partner apparatus based onthe value of the Parameter subfield.
 7. The communication methodaccording to claim 6, wherein an expected reception power at the PCP/APcommunication partner apparatus is estimated by using the value of theParameter subfield, and inequality between the estimated expectedreception power and a receiver sensitivity value is checked by thenon-PCP/AP communication partner apparatus.
 8. The communication methodaccording to claim 7, wherein if the estimated expected reception poweris equal to or less than the receiver sensitivity value, the A-BFT isskipped.
 9. The communication method according to claim 6, wherein thevalue of the Parameter subfield is obtained by subtracting the receptionantenna gain from the transmission EIRP.
 10. The communication methodaccording to claim 9, wherein the value of the Parameter subfield isobtained by further subtracting an additional gain from the transmissionEIRP, the additional gain being a difference between a receiversensitivity value and an actual receiver sensitivity value.